Having a similar problem on 295.20.
I'm using gnome 3.2.1. on gentoo with kernel 3.2.9-gentoo. LCD is HP ZR30W.
When the screen is locked, the running apps dont respond anymore.
My downloads just stop
. And Mozilla Thunderbird doesn't receive email.
When I unlock the screen the downloads run again!?
When I get home from work I will attach a nvidia-bug-report.