The problem:-When you open Task Manager by pressing three keys-[CTRL]+[ALT]+[TAB],it appears for a second or two then disappears.
Why does it happen?
If there is virus infection.
What to do?
Check whether regedit,msconfig tools are also disappearing or not.You should scan the system with latest virus definitioned antivirus.
Win32.Cydog.C@mm ( Win32/Kickin.A@mm / I-Worm.Cydog.c / W32.HLLW.Kickin.A@mm / WORM_CYDOG.C / Win32.HLLM.Cydog )
Emergency Tool to revive the Task Manager:-
Create Emergency Copies of Critical XP System Utilities (Regedit, MSConfig and Task Manager)
By courtesy Doug Knox,MS-MVP