Comment # 62 on bug 105251 from Michel Dänzer

(In reply to Benjamin Hodgetts from comment #61)
> [...] this problem has changed in how it manifests itself. Previously you'd get
> the "[gfxhub] VMC page fault" messages. Now it manifests itself in considerably
> more serious looking errors (with none of the "VMC page faults" in sight).

That might be a different issue, please file a separate report about it.