oops, seems I forgot to report back. As already mentioned in comment #8, this is solved with kernel 3.6.0-17.27
I have since then upgraded to Raring and haven't seen this happening again, even without a BIOS update. Since there is no Windows or Lenovo partition on this laptop anymore I wouldn't know how to upgrade the BIOS anyway.
oops, seems I forgot to report back. As already mentioned in comment #8, this is solved with kernel 3.6.0-17.27
I have since then upgraded to Raring and haven't seen this happening again, even without a BIOS update. Since there is no Windows or Lenovo partition on this laptop anymore I wouldn't know how to upgrade the BIOS anyway.