XBMC playback probz

When I watch movies with XBMC, so the movie stutters with both picture and sound. It’s impossible to watch a movie. If I use Media Player then picks it not with the same film. Would like to use XBMC because of file types. Have tried to uninstall XBMC, but it will not succeed properly.

Someone who knows about the bug or?

After just upgraded to v.1.1 and it helps nothing. How can I installlere all the software again?

Thanks in advance