Lenovo Thinkpad E520 about 14 months old, Kubuntu 12.04 LTS, all current patches. Dual-boot Win7.

Intermittently goes into grub rescue at boot time. Message "partition not found". It does this maybe 5% of times on power-up. After a few power-down, power-up sequences, the problem goes away and I am able to boot fine. (I don't know what valid grub rescue commands might be useful.)

All of the references I google seem to be for when this happens every time. Most refer to repairing the MBR by using lilo. This does not seem to be to be a solution for an intermittent.

Suggestions? Thanks,