isass.exe - system error

[Julie]

I'm trying to fix a friend's HP notebook running Win XP Home Sp1.

Whenever the computer boots up, it will get to just past the splash screen and then I get the error message "isass.exe - system error. Name object not found".
So far I have tried (after clicking F8) Last good configuration, Safe Mode and Safe Mode with Command Prompt - hoping to restore the configuration or get access to System Restore.
Each time the computer just reboots after I click on my option, followed by the same error message.
I tried to do a Repair Installation from Recovery Console but the same thing happens. The installation will proceed, reboots, then says "Setup is restarting",
then the error message again.
I have heard its possible to do a manual repair from Recovery Console - but don't know how.
I would be very grateful if someone can give me instructions for this or other advice.

I'm told isass.exe is a trojan, but I can't get rid of it cos the computer won't boot.

[faulkner132]

Co-worker had this problem, we essentially backed up all her important documents through a Linux Live CD and then wiped the drive. All of the solutions we found either didn't work or produced even more problems.

[Julie]

Thanks for that.
I did what you advised except, because I couldn't get a Linux CD, I used a recovery program.
Now the next thing I have to do is make sure this doesn't happen again.

[faulkner132]

It's caused by a trojan which reconfigures Windows use of "isass.exe" to "lsass.exe" (L instead of an I). Windows then then can't boot because of the corrupt file.

Best prevention would be good anti-virus software (AVG is a good free one) and some anti-spyware programs.