I installed a new NVidia graphics card in my desktop PC a couple of days ago and started experiencing total desktop lock ups after about 5 minutes while running Beryl or Compiz.

It doesn't appear to be distro specific as I tested it out on several different distros, Debian based, Slack, and RPM based. Same on all.

After a lot of googling and reading to no avail, and a lot of tinkering, I think I finally hit upon the solution.

Using the NVidia Setting app disable vertical syncing.

Do the same in the Beryl Manager and/or Compiz config.
Restart X.

I hope this helps someone who may be pulling their hair out over the same problem.