I have a fairly new desktop running XP-Pro SP2, and after the computer has been on for 15 to 30 minutes I get a blue error screen with the message "driver_irql_not_less_or_equal". This message also comes with the message "iastor.sys - address B9D5D25F base at B9D4E000". The error occurs whether or not I am running anything.

I have tried the following:

Using system restore to a point before this problem occurred. (no effect)
All devices other than mouse and keyboard have been removed (no effect)
Plugging the mouse and keyboard into different USB Ports (no effect)
Swapping out one at a time each of the four memory sticks (no effect)
Running ChkDsk /f on start-up (it crashes before finishing)

I also tried to reinstall windows and ran into the following problems:
If I run the windows setup after booting it says that I cannot since the CD that came with the computer is SP1 and I have SP2. When I boot off of the CD the computer freezes when it reachs the first set-up screen (where you can choose to repair or reinstall) and I cannot proceed.

I am running out of things to try. I am not quite ready to rebuild from scratch, especially without knowing what is wrong. Any suggestions?
Thanks,   Rick
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I have seen the "driver_irql_not_less_or_equal" error message a couple of times.  Once it was on an older laptop and was attributed to the USB wireless nic that was installed.  We could not get it to crash at all with it removed.  The only other time I saw the error was on my current computer when I had some bad memory.   After replacing the faulty module, problem went away.

iastor.sys for my system is the intel RAID driver.  If you are using a RAID setup, you may want to check the health of the volume.  Not sure if that driver is only used for RAID setups, but it may be worth looking into.
As noted above, i think too iastor.sys if for sata/raid. The BSOD driver_irql_not_less_or_equal is offen associate with bad memory. You can check your memory with memtest -  - direct link to burn the iso image Extract and burn opening the image in softwares ike Nero (don't just move the file) using Open -> Image or just Open comand.
The error always return the same adress (address B9D5D25F base at B9D4E000)?

You can test your hd too to make sure they're ok.
Western Digital:

Or you can download UBCD, a bootable cd that contain several utilities, between them hard disk test.
Change ide cables and assure that they are ata66! I recommend ribbon ones for test porposes.
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rcl2884Author Commented:
Well, I ran the memtest procedure and the memory is fine.

I am not using a RAID setup.

I ran the seagate utility that was contained on the UBCD ultimate boot CD. This seemed to start up OK, but after about 10 to 15 seconds dumps me to a DOS screen that says I need to reboot before running any additional utilities. Should I conclude that the Hard Drive is bad. Shouldn't I be getting some sort of diagnostic screen?

In a perhaps related question, prior to my first post, I ran ChkDsk and set it so this would run when booting. This procedure does not run successfully, stalling when the first test is 20% complete. Initially I got the blue screen with the "driver_irql..." message, but now after a couple of attempts, I get nothing. It just hangs midway through the test. Since it always starts ChkDsk, I cannot boot successfully at all, now. Is there anyway to stop the system from running ChkDsk on startup?  I did not see anyway to get at this in start-up. Is this another clue that the hard drive is bad? Anything else I should try before concluding this?  The system is maybe four months old so a bad drive seems unlucky.

oh, and since I cannot get past the stalled chkDsk procedure,  I don't know the answer to the questions about the error occuring at the same address

... Rick
Can you boot to safe mode?  You may be able to disable the checkdisk there.  Press F8 while booting to see advanced startup options.  If the checkdisk still tries to start even when booting to safe mode, you may have to try something else.  

Is it possible to check the drive in another computer?

Even if you don't have RAID, i think this file is for disk management in the windows (your hd is SATA?), and probably was installed in a install package.

Seagate SeaTools inform the result of test, showing either if the hd has problems or no. Please download the SeaTools and burn they direct on a cd (

About the check disk crashing: i think this is really a clue, togheter with the error involving iastor.sys, that the problem is your hd.

You're not unlucky, hd's tend to fail so easy in nowadays. Always keep a backup and *never* trust them.

Power supply with problems can manifest errors in hd's  (or damage them) or in others ways, but now concentrate in your hd, since they appear to be failing. Please test again and keep us informed.
Be sure to have a good psu, even good models sometimes fail and compromise the entire system, and get one with enough power to your system.


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rcl2884Author Commented:

The seagate diagnostic did run and revealed a bad sector. (This is a SATA drive). I had run a recent backup (using retrospective) but had never created a rescue boot disk. Embarrasingly enough I did not since the program asked for my XP registration number which I could not seem to locate. So I guess my best bet is buy a new drive, reinstall windows (if I can find that damn number) and then reload off of the back-up? Is there any point in trying to ressurect this drive or should I just toss it? Any chance I can disable ChkDsk on boot-up (does not work to go into safe mode... it still runs ChkDsk) so I can take one last look for anything I might want to save?
Thanks,  Rick
If your drive is a Seagate, seatools can repair the bad sector , and other system softwares can do too (for your hd's). Otherwise, can be just software problem (a problem when recordin in the sector), and a full format can help to resolve this problem, but just for bad sectors. I don't remember if the SeaTools have the format option for all hd's, but if have, you can use. Yes, you will need to reinstall again the windows, and i don't know how to disable chkdsk on boot-up.

UBCD for windows can help you moving data etc, they have the windows gui and several other utilities not only from windows but too other helpful utilities.
I don't remenber if they can load a existent windows instalation and use the System Restore, but if they can do, you will be done. Or use the tools to help accomplish your goal.

And last, chkdsk don't crash just for bad sector, well, i think that is hard to happen, maybe it's more than a simple bad sector.
rcl2884Author Commented:
Maybe I was too quick to assume it was just a drive problem. I guess SeaTools tried to repair the sector but could not. While ruinning I get a message that it will atempt to fix bad sectors, but when it finishes, it simply says that the test "Failed". There is not mention of any attempt to fix.

Secondly, the diagnostics screen lists two drives. Under "unknown Controller", it lists a BIOS drive, but it also lists the drive under "Other Seagate Drives". Is this normal? "Both" drives pass the quick test. Just for the heck of it I am running the BIOS drive through the full test. Last time I did this on the "Other Seagate Drive". I don't want to prolong this past the point of diminishing return. I will accept your help as the answer and proceed to reinstalling windows.... first on the old drive, and then if this does not work on a new drive. Does this sound like the right approach at this point?
... Rick

Hi Rick,

I don't have viewed yet or don't remember this option in SeaTools, but i think it's mormal. You have two drivers now? Then it's just this, they don't recognize correctly the driver controller or read the same information from the bios, well, its my bet.
If failed to fix your hd, them the hd is not more good, because new models without problem they fix.
Your two hd's are Seagate, right?
And for the problems showed, i think your old hd is bad, maybe they start to work after a instalation but the problem will come back later. It's not normal chkdsk crash and seatools don't fix the hd. You can test the old hd reformating but don't trust it.
rcl2884Author Commented:
I am sorry I was not clear. I only have one drive, but it shows up twice in SeaTools. I was wondering whether this might be a symptom of something else? I will try reinstalling windows on a new drive, and maybe I can read the old one once the new one is installed. I do not have another computer with SATA to test.

Thanks again,  Rick
Hi Rick
Don't worry about the the hd showing twice.
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