Can't create new XVID files

[WARP MAN]

I have two problems - which may be unrelated, but here goes.

Firstly, I have a digital video camera. I used to convert all my video off this to XVID (with MP3 sound) fine.

However, now, when I create an XVID file (in numerous tried programs), Windows always receives an error. The XVID file appears to be created fine in the program, but when I click on it in Windows I get a 'send error to microsoft message'.

I have all my old XVIDs on my pc which al play fine and receive no error.

I have reinstalled the XVID codec but the problem remains.

....
Maybe unrelated but:

When I start my pc I always get a little pop up which says:

"WINDOWS MEDIA PLAYER IS NOT INSTALLED PROPERLY AND MUST BE REINSTALLED"

I have done this but this still pops up everytime. WMP works fine though, there appears to be no problems (maybe except the above). It's WMP 10.

Any ideas appreciated, the not being able to create XVIDs is highly annoying.

[celtic_druid]

These avi files? If so then it could be MS's buggy thumbnail shell extension causing explorer to crash.

[WARP MAN]

If that was the case, would I not be able to play the file (behind the windows error message)?

[celtic_druid]

Sure, but not by opening it via explorer.