Sounds like a variation of the 32.Spybot.worm Virus. It prevents you from
opening system programs like regedit, msconfig, task manager, plus many
more. This virus has been making its way around the internet for the second
time so I have been told.
One variation of this virus is called the WINCFG.SCR.
You can read about this worm and its variants here:
http://forums.techguy.org/t154820/se2af3281b8ed5b12d9ab63ce601577d1.html
or here:
http://www.annoyances.org/exec/forum/winxp/t1047314957
Removing this virus will take a little bit of know-how. The first step will
be finding out the name of the infected file. If the two links above don't
supply you with enough information, do a Google search, and type in the name
of the virus.