Processor context corrupt.

Hi dear all,

We have a dell server (poweredge 1950) running in production over a 3
years from now. But since the last 4 months the server begins to
randomly crash, sometimes once a month, sometimes two times a week.
This is the error log:
http://imageshack.us/f/714/screenshotat20111209210.png/

Any hint on this?
Thanks!

-- 
Marc