PC to TV - invalid format?

[tigergs]

hi recently i bought a 42" lcd tv which i hooked up to my computer from time to time everything worked fine now all of a sudden it says invalid format??if anyone could shed some light on this i would much appreciate

 

[Tmagic650]

Make sure the PC is sending the right vertical refresh rate to the HDTV. Look in the video display settings of the PC. Match the PC to the TV

 

[davisjaron]

to back up what tmagic is saying, go into your graphics card settings and make sure that you didn't change any settings that were too high for the TV, such as setting 120hz to a 60hz tv, or the resolution to an invalid setting for that tv... anything like that could make it not show up on your tv.