I have over the last 2 months experienced seemingly random system freezes on a Lenovo w520 (HD3000 Sandy Bridge) and a Lenovo w530(HD4000 Ivy Bridge) machine. Both running OpenSuSE 12.2. I have read many forum threads and tried a few things without success. The logs are not very helpful as nothing specific seems to be the problem and I suspect the freezes prevent the logs from being written. A hard reset is needed to get the machines going again.
I have noticed that on the current HD4000 system I cannot select OpenGL as the Compositing type when booting with the HD4000 adapter. Using the discrete nVidia (K2000) works fine however. I do not know if this happened on the w520.
I also had both machines working correctly by not installing what I thought were pertinent graphics/XServer/Mesa/KDE4 related updates after the initial install. I attempted to do the same during subsequent installs but somehow included an update that seems to produce an unstable system.
The w520 machine is no longer available for debug purposes as it has been replaced by the w530. I think it noteworthy that the freezes happened on both Sandy Bridge and Ivy Bridge, although I do not know how this might be useful to pinpoint the problem.
I have limited knowledge of the intricacies of graphics drivers / XServer /Mesa interactions and am looking for help in getting to the bottom of this. Possibly increasing debug output or other diagnostics to get the machine running correctly.