i've the same problem && the same errors!! with my gtx560:
-I installed (fresh)BT5-r3 (kde64) with (4.2 & CUDA driver 295.xx) during pyrit benchmark or piping (crunch / pyrit / cowpatty or other) my pc crashed after(25000 PMKs/s)(in-X)or rebooted (out of x)! i update my CUDA to 5.0.35 but .. nothing, same problem!
I blamed KDE (for continuous desktop-crash) &&.....
-yesterday I decided to install BT5-r3 gnome64 with CUDA 5.0.35 & 304.xx driver but the problem remains!!
the only thing that still works without problems with cuda 5.0.35 is my notebook (nvidiaGT-420m) which features a BT5-r2 (kde64) UPGRADE to R3