Re: Random crashes, NVRM Xid messages
I was having the same issues (screen corruption, random lockups in that lockup, let go after 3 seconds then total lockup, then black screen after another 20 seconds or so. Happening every couple of hours), and I couldn't figure out what combination of software was causing it. (kernels 3.2.11 to 3.3.4, nvidia 295.20, 33 and 40). This is on a GTS 450.
Going back to glibc-2.14.1 (from glibc 2.15) and nvidia 295.20, while removing one of my two monitors and disabling TwinView seems to have done the trick, although it's only been one day. Just one data point for something to try.
(For those that are not aware, downgrading glibc version is very risky so don't try it unless you know what the issues are)