Sometimes when you’re really busy and you’re under time pressure to get things done, it’s all too easy to overlook something and cause yourself a whole load more work to do.

I’ve been trying to diagnose why a PC will not work reliably.  Every month or so, it trashes the registry on shutdown requiring a manual system restore.  It’s very frustrating because no matter what we do to the machine in the shop it will not repeat the fault.  All of the relevant diagnostic tools report no fault found, even after allowing to run repeated extended cycles.

Other than a Windows installation that won’t boot because of a corrupt registry, the only other symptom I’ve noticed is quite a lot of rather odd filesystem corruption.  The sort I haven’t seen since the old Winchester Hard Drive and DOS days.  For instance, there are 4 “Windows” directories, one true one and several with one corrupt character in the name.  Running chkdsk didn’t solve the problem, and the manufacturer’s hard drive diagnostics passed, as did the ever helpful Seagate tools.  After several scans and analyses with different antivirus and malware investigation tools I was reasonably convinced that it was not malware causing the problems, but what is then?

Well with the hardware all reporting fine I thought it was about time a repair install of Windows was done.  OK, boot from CD and start the repair process.  The file copying stage stopped twice with file copy errors.  The first time it carried on when pressing retry, the second time it wouldn’t budge.  The CD was almost new and had been successfully used earlier so that wasn’t the problem.  So, I told it to skip the file and it merrily carried on.  End of the file copying comes and it’s time for a reboot.  Oh.  PC reboots, and then reboots, and then reboots.  It’s a familiar problem – a Blue Screen of Death or BSOD on boot.  No matter, reboot, use F8 to get the boot options and then disable automatic BSDO rebooting.  The BSOD happens to be a Stop 0x0000007E (0xC0000005, … ).  A quick web search throws up nothing particularly relevant.  Back to the drawing board.

Now I thought I would try another hard drive, just in case this was causing the problem.  I imaged the old drive to the new drive and tried to boot.  Same stop error.  OK, retry the repair install.   Nope, still BSODs.  I was really beginning to lose the will to live at this stage.  Interestingly the filesystem corruption still appeared to be there on the new drive.  Chkdsk still didn’t help.  Odd, I thought, OK I’ll delete the image and instead of imaging, I’ll do a file by file copy to the new drive.  That way it shouldn’t keep corrupting the filesystem.  So, I did that and after an hour of chasing my tail trying to get the partition recognised as a bootable partition and get the PC to boot from it I gave up.  I found an old CD I made which enabled the system to boot from the first partition of the first hard disk (using a boot.ini style arrangement).  System started, BSODed and then rebooted.  Same BSOD as before.  BUT it started in Safe Mode.  What now?  Well I tried deleting all of the third party drivers from c:\windows\system32\drivers and tried all of the usual msconfig.exe options for diagnostic booting but still no joy.

By now, I’d transgressed from losing the will to live to down right insanity.  I decided then to go back to the drawing board.  Look up the Stop 0x0000007e error again and unsurprisingly, I’d missed the one article that would’ve told me what to do.  Of all the rubbish written by armchair experts on the Internet was an article from Microsoft which lays the blame at the foot of the Intelppm.sys file.  Then it all came flooding back.  I’d seen this very same problem before and again at the time spent a whole weekend before I figured it out.  You’d think that after that hardship the solution would be imprinted into my brain, but sadly not.  So, after deleting the Intelppm.sys file (which only works on Intel processors, not AMD) from c:\windows\system32\drivers Windows can complete the repair installation.  Except that the file copy errors still persist. 

Running out of ideas I decide it’s time to swap the RAM and see what that does.  That cured it!  No more file copying errors.   Did it work now?  No.

The next problem was as soon as the GUI portion of Windows XP setup started, a box popped up moaning that it couldn’t locate asms.  Hmmm, not seen this one before either.  Back to the web.  Luckily I found the solution straight away this time.  Shift-F10 to get a command prompt, run regedt32 and remove the UpperFilters and LowerFilters from ControlSet1\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318} in System.sav.

Was that the final sticking point in this never ending saga?  I’m not really sure yet, but I sure hope so!