Bunch of problems with Win XP Pro: error 800b0100, cannot boot up Windows after trying to repair it. It's a mess.

Hi everyone,

A few days ago my laptop started behaving odd after I logged in. I scanned it for viruses but the problem was still there. So this is what I did:
I booted up my laptop from the Dell Windows XP OS CD that came with it.
I see the blue screen that says "Windows Setup" at the top with the gray bar at the bottom that says "Setup is loading files... "
Of the three options I get, I choose the option "To setup Windows now, press Enter", then I accept the end-user agreement.

The first time I did this, it copied the files it usually copies, and then asks me what I want to do. I tell it to repair the already-existing WIndows installation. It does all it has to do an then I see the more user-friendly WIndows installation screen that tells me how long it will take to install.

It tells me it will take 39 minutes to install and almost immediately I get a messagebox with message "Fatal error: Setup failed to install the product catalogs. I click OK and I then get error "The signature for Windows XP Professional Updgrade is invalid. The error code is 800b0100".

So after I try this, Windows doesn't let me log on normally of in safe mode. Everytime I turn it off and back on I automatically get the "Setup is being restarted..."

I tried renaming directory catroot2 to catold (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q307153) but that doesn't work.

What else can I do? I cannot go into safe mode and I cannot start up WIndows normally. I wanted to back up some stuff, but I don't want to do it via the command prompt.

I have WIndows XP Pro SP2 (not an upgrade) and it's the same exact copy that came with the laptop when I bought it. I haven't installed any new software. This is the first real problem I've had in a long time.

Any help is appreciated.
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Firstly, I would suggest backing up your stuff. This is easiest to complete by removing the hard drive, mounting it in an external hard drive case, and plugging it into another computer (friend, parents, etc). You can then copy various things off it.
  A better way is to make an image of the hard drive, using something like Acronis True Image Home. This will be able to copy system files, hidden files etc. Basically, you can either boot from the Acronis CD (which can then copy stuff to an external drive), or you can use an installed version on a different computer.

I would then suggest you check the components of the computer using a CD bootable option. I tend to use the included tools of the Ultimate Boot CD (Free) to stress all the components and test whether they are the cause of my problem.
Make sure to test the Memory, CPU and Hard drive. Mainboard tests are difficult, and usually don't result in anything substantial.

If everything turns out normal, you can either try reinstalling windows (better option) or repairing your previous install. If you are going to try the latter, then you need to use the actual Windows XP Pro SP2 disc that you have (as long as the windows you have installed is also the Pro SP2 disc). Be aware, if you are using an OEM disc to repair a retail install, it won't like you very much and can throw errors. Try to use the same disc that you used to install in the first place.

The repair installation option is alright, but I think a reinstall would provide you with a better start point for future work.

I tend to find the need to reinstall windows every 6 months so I can clean out all the gunk that accumulates in the registry in that time.

Hope this helps.

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Test your RAM using memtest86+ and also test the HD using the disk manufacturer's diagnostic tool. You'll find both on the UBCD.

to get you started, try this :

then you can do what you want...
MyersAAuthor Commented:
Thanks for the posts. I downloaded Ultimate Boot CD.

I tested my RAM and I got a bunch of error messages with one of the modules. Would it be possible that I get errors because there's a problem with the RAM slot?

The reason I asked is because I inserted the faulty module in one of the slots and I got a bunch of errors. Then I put it in the other slot and the test passed. On the other hand, once I rebooted the laptop I got an error memory. So I'm almost certain that it's the memory module.

Can the memory slots be tested with the UBCD?

Out of curiosity, do you guys know how I can replace a GigaRam memory module that is supposedly under warranty? I only have the module (no receipt, box, etc...)

>>  I tested my RAM and I got a bunch of error messages with one of the modules. Would it be possible that I get errors because there's a problem with the RAM slot?    <<   thet is possible, yes

you test ram, not slots - but the signals pass thru the slots, so...yes they are tested too - clean the slot thoroughly

>>  how I can replace a GigaRam memory module that is supposedly under warranty?   <<  bring it back to the supplyer
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