Thanks guys. Yeah, I removed the hard disk before sending it in. Not only would I fear repair services of accidentally deleting my data, but I wouldn't want them to browse through my holiday photos.
I am glad this notebook is still under warranty. My previous notebook, also a Lenovo Thinkpad, died of a similar symptom (the GPU failed due to a crack in the solder joint, a common problem with notebooks I heard). Last time it was beyond warranty, and a system board replacement would have cost more than the used notebook was worth.