Dr. Watson c0000005 (access violation) on multimedia players

This must be a tough one...I've seen other topics concerning this message in the past week or so, but no replies

c0000005 (access violation):

I get this error every time I attempt to play a file in any multimedia player I have.

The machine is a dual 466 celeron running a new install of NT4.0 Workstation.

For several days I was able to play avi and mpg files on MPlayer. Then one day last week, I started getting the access violation message.

I have downloded the newest MPlayer and installed Service Pack 6a, to no avail.

Any help on this problem will be greatly apreciated.