Playing video in any format crashes system

No matter what source I attempt to view video (online newsfeed, downloads,
etc.) my Media Player will start to play the file - screen goes to black for
a few seconds - then my entire system locks up and the only way out is to
power down. There's no error messages since it completely crashes my system.
I was hoping a recent update would have resolved t he issue, but this has
been going on for months.

I have Windows XP, SP2, WMP 10 and all associated updates. I have my
options set to download codecs automatically (whatever that means. I don't
know or understand anything about codecs) - I just want to be able to view a
video file on my system without crashing.

I don't know if the solution is to uninstall the WMP and go to the site to
reinstall or what. Can someone please assist me in finding a resolution to
this?

Thanks very much,
Lisa