Some people have had probs when trying to play videos with WMP & LW 5 but VLC has fixed it for a few people (I realise it hasn't helped you).
Were you using WMP for video before you tried VLC?
If you were - just check your file associations within WMP in case it's still trying to associate with video files.
In WMP go tools > options > file types. Untick the video formats that you don't want WMP to play > apply > ok.

After that, try previewing or launching with VLC & see if things are any better.


Do audio files launch ok?