You most likely have a virus.
[[When you open System Configuration Utility [MSCONFIG], Registry Editor or
Task Manager, they flash for a second and quit. This symptom is caused by
Viruses.]]
Task Manager, MSCONFIG, or REGEDIT disappear while opening
http://www.mvps.org/sramesh2k/ToolsQuit.htm
Update your antivirus software and run a full system scan.
Update whatever anti-spyware applications that you have and run a full
system scan with each one.
You might want to start in Safe Mode to run your antivirus and anti-spyware
software.
Running a full system antivirus scan or anti-spyware scan in Safe Mode can
be a good idea. Some viruses and other malware like to conceal themselves
in areas Windows protects while using them. Safe mode will prevent those
applications access and therefore unprotect the viruses or other malware
allowing for easier removal.
How to start Windows in Safe Mode Windows XP
http://www.bleepingcomputer.com/forums/index.php?showtutorial=61#winxo
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Hope this helps. Let us know.
Wes
MS-MVP Windows Shell/User
In