I've a computer with Windows XP service Pack2. When I try to make
chkdsk /f, after the checking is finished and the computer is restarted
I receive the FOLLOWING message:

"A problem has been detected and windows has been shut down to prevent
damage to your computer.

SESSION5_INITIALIZATION_FAILED

If this is the first TIME you've seen this Stop error screen, restart
your computer. If this screen appears again, follow these steps.

Check to make sure any new hardware or software is properly installed.
If this is a new installation, ask your hardware or software
manufacturer for any Windows updates you might NEED.

If problems continue, disable or remove any newly installed hardware or
software. Disable BIOS memory options such as caching or shadowing.

If you need to USE Safe Mode to remove or disable component, restart
your computer , press F8 to select Advanced Startup Options and the
select Safe Mode.

Technical Information

STOP: 0x00000071(0x00000000,0x00000000,0x00000000,0x00000000)"

After I restart my computer another screen appears which prompts me to
select Safe Mode or Last Good Know Configuration or to Start Windows
Normally. If I select Start Windows Normally then the same thing
happens. If I select Last Good Known Configuration the computert logs
in.

What's  the problem? Before Service Pack 2 I don't think that I had
that problem.
Is there any virus? How can I solve the problem?There's a LOT of Google entried. Here's one:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/DevTest_g/hh/DevTest_g/t05_bugs_60_d2e43256-faf7-49da-beed-a2de62c80fb5.xml.asp

Here's 546 more:

http://www.google.com/search?hl=en&q=SESSION5_INITIALIZATION_FAILED+&btnG=Google+Search