[copulater]

I have tried to unstall and reinstall but i still get invalid file format on all files,even the ones that i have watch thru XBMC

[mad-max]

What files are you trying to play on which version of XBMC?
Maybe you have a sample?
Do they play fine in other players?

You might provide a log file for the process you are doing:
http://wiki.xbmc.org/index.php?title=Log_file#Location

cheers,
mad-max