Help With Cleaning Up Unused File Extensions In Registry

Is it safe to delete all file extensions in HKEY_CLASSES_ROOT that say "This file does not have a program associated with it for performing this action. Create an association in the Folder Options control panel." when I try to open a file with that extension? Thanks
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killbradConnect With a Mentor Commented:
Yes.. but I would be very careful.. don't delete exe, com, pif, cmd, scr, .. etc, etc...

So in otherwords.. no.
orangutangAuthor Commented:
And I forgot to mention that I already know about all of those registry optimizing programs. I'm just curious. How they work and why there are so many file extensions that show that message when I open a file with that extension.
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orangutangAuthor Commented:
What about something like HKEY_CLASSES_ROOT\.386? I get that message when I open a file with that extension but it also says its perceived type is "system".
megs28Connect With a Mentor Commented:
That's for VXD files = Virtual Device Drivers.....used by Windows.

I would strongly suggest you not delete entries from that registry's very risky and contains more than meets the eye.  There are TONS of different file types that don't have associated programs with them that are required by the OS.  You will do permanent damage to your OS install if you delete one entry that's required.  If you want to cleanup file extension types that don't have programs associated with them do so under the "File Types" tab in Tools --> Options in a Windows explorer window.  If you insist on playing with fire, do a full system backup (ie. Norton Ghost) prior to doing so.
orangutangAuthor Commented:
Of source I did a registry backup! How stupid do you think I am?! ;)
I've sort of made a goal to learn how Windows works a little better. That's it :)
bmilne1957Connect With a Mentor Commented:
A wise man learns what he needs to know and leaves the rest alone. I'm on a need to know basis. Focus on connectivity, on configuration and any utilities that will help you understand XP better. You may delete something you know you do not need now, but will prevent you from acomplishing something in the future as "things" change.

You will be rebuilding your PC if you mess with the registry much. For practice - try removing Norton Antivirus from your PC via the Registry and explorer, that will give you a crash to remember and future caution concerning the registry.

Good Luck
orangutangAuthor Commented:
Well, I guess I'm not a wise man at all :)

So why should I not delete the .386 extension if when I try to open a file with that extension, it gives me the message?
pheidiusConnect With a Mentor Commented:

In general, I agree with megs 28. I am hearing you say, though, that you want to learn the eitiolgy, not just the do's and don'ts. The following definition, I think, contains within in it a more specific infered why.

VXD - A device driver that runs under the Windows operating system. It runs as part of the OS kernel and has access to kernel memory, running processes and hardware. Starting with Windows 95, these files have the file extension .vxd, and before that with Windows 3.x, they had the extension .386.

Windows has been crippled for years by having to deal with retroactive compatability to previous windows versions. This is whu Mac OS X has taken such a dramatic OS lead cuz they killed of their Clasic version and just started over. Many of Windows issues and much of why Vista took 5 years to get out goes back in major parts to this issue. So if you are going to clean your registry of .386 files this is what might happen from best to worst.
1. Your registry gets  a little smaller with no difference in any performance issues + or minus.
2. You can no longer run any legacy programs from  windows 3.1 days: your machine crashes anytime you try.
3. Programs that you still have unbeknownst to you had 3.1 roots and, therefore, themselves have retro 3.1 support built in and won't run and/ or crashes your machine.
4. Your copy of Windows XP Pro  service pack 2 smells a 3.1 app next door and crashes constantly... a la from the above definition,"It runs as part of the OS kernel and has access to kernel memory, running processes and hardware. God, do I remember the days of Windows 98 blue screen of death .vxd fatal errors.
5. Pieces of windows XP Pro service pack 2 decides that parts of it itself are Windows 3.1 and refuses to ever run again.

So , in any case, I myself have broken many perfectly good things trying to fix them and have learned stuff in so doing but, in the case of the registry, why reinvent the wheel? There are good appz out there that will clean and compact your registry ranging from free to pricey. I, myself, am using a copy of JV16 powertools that worked with Windows 98 and still works with win xp.
orangutangAuthor Commented:
Okay, so how do the registry optimizers tell if a file extension is invalid?
MereteConnect With a Mentor Commented:
Hi the main reason you get this message I believe anyway is because its windows way of keeping you out of there,
there is some places novices and even moderate experts should never go, windows knows full well what opens it or is using it but its non of our business and its probably criticale to the running of some program within windows.
How do the optimizers know?
Windows has a basic structure the regestry that windows is built on  everything else is not windows in itself so is not deemed windows critical, once it scans the windows regestry and checks it internal scripts against the regestry it will then pick up all the other stuff.

To determin what is system critical and what is not can be very technical, some programs such as AV and firewalls write into widows, and removing them incorrectly like not uninstalling them so that windows will let go of it can cause a gap in the flow of information,
 these are what slows down the system over periods of time causes lockups and crashes.
Gaps in the flow of information to an electrical based instrument as a computer is, is critical, defragging helps.

How To Use A Registry Cleaner

hope this  gives you a picture.
TSI-WLVConnect With a Mentor Commented:
CCleaner has always done a good job for me plus its free. It will also clear out all kind of temp files you didnt know existed.
WmOfTewksConnect With a Mentor Commented:
I just came across this,, and gave it a spin on my home machine -- you know, the one I use all the time and have no backup for  ;-)  And I actually had no problems.  I compared it to another Registry cleaner I had been using (name escapes me) and the new one found about 1000 entries to clean where the old found less than 100.

This provides for a full Registry backup and an XP restore point just in case everything goes to he** in a handbasket.
orangutangAuthor Commented:
Actually, I know of all of the "best"/"popular" registry cleaners. They are CCleaner, Registry Booster, Registry Mechanic, System Mechanic, Reg Organizer, and WinASO Registry Optimizer. I've tried all of them and I have found that Registry Booster if the "best". Although Registry Mechanic seems to be the most popular, its deep scan isn't very accurate. Registry Booster found over 3x more errors compared to Registry Mechanic with the Deep Scan unchecked. And most of them were accurate. I was checking around on and I found the user reviews for Registry Booster and It didn't get very good reviews because it said that it had a horrible trial system and customer support.
I am not even going to pretend that this answer is definitive but I think that the answer lies in knowing the difference between a string and a thread. An optimizer must follow the string data from a particular registry entry all the way through the gui shell : through all the directories, folders, etc: all they way to an executible if not back again through all  the other string data/reg entries an executable needs with which to run.

The following is a snippet from an experts-exchange thread discussing a fix on one lone invalid extention issue.

Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long

Then from a form you can use:
ShellExecute Form.hwnd, "open", "MyDoc.doc", Chr$(0), "C:\Temp\", 3

This exchange went back and forth in detail like this for quite a bit.

So, in short, I think you have to be a very competent Windows programer to answer or understand the exact answer to your question.

orangutangAuthor Commented:
Well, I sort of made a registry error deleter a while back ( that was based off of some other registry searcher. But I've learned a lot of stuff about the registry ever since so I have a slightly more updated version that I'm working on.
Well, I am a bit confused now. You seem to know more about the answer to your question then does anyone who has responded(including myself). I would close this thread and rephrase your question in  data string specifics so that only other programers can answer. This would lock out noobs like me from wasting your time.
orangutang  the best way to clean out the regestry is to delete the partition and clean install, I favour this approach at least 2 twice a year, I have 3 hdd, 2 with a full operating system and one large for all my data files programs etc,  I keep one bootable as a spare incase one windows fails ..
where possible I dont install anything to C drive its on a separate hdd, the reason !! most trojans and viruses target windows.

so  everytime I format windows re-install clean, I swap the hdd and slave the old windows and reformat it and backup my original again liek a viciuos circle, its very rare that I do this from some malware or failed windows, windows runs better as the pagefile is on another hdd too.

 I just go to my E and f drives for my stuff, I create shotcuts from the .exe of games and programs that will run from there to my current desktop.
I also move my store folder for my emails off the C drive makes it easier to import them later.
And guess what  teh games and programs on my slaves none are now regestered in the regestry either which makes them less a target as well.
it is a win win combination.
You can use external drives in external cases slaved  keeps them away from the source of the misery, Windows :D

orangutangAuthor Commented:
I think I'll just post another topic regarding the registry. I'm more interested to know the specific sections of the registry such as what kind of information is in the HKEY_CLASSES_ROOT\CLSID key.
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