can't play my movies correctly - Please Help

[todtliat]

I don't know what exactly I have done to cause the problem but now When I try to play movies on my computer they are not shown completly. Meaning I get only a square frame of the picture. It doesn't matter which movie player I use. Before this catastrofy happened I was trying to play movies from my PC to the TV and among other things I installed the program Tvtool v9.5.5.3. I deinstalled the program but the problem persists.

Sys details
P4 win XP home
nvidia GeForce FX Go5600

Can anyone Please Help?
Thx Liat

[DAvenger]

Installed any codecpacks recently? Could you post a screenshot of the problem?