I wrote:
I had a similar problem with Lenovo T500 yesterday. It was not reproducible reliably, and oddly the symptom is completely gone today.
There is a bug report against kernel 2.6.34.6-47:
https://bugzilla.redhat.com/show_bug.cgi?id=629291
with a possible fix.
Ouch. After hit the send button, I restarted the laptop and closed the lid and it went insomnia and I had to force shutdown. This is with the new kernel 34.6-49 mentioned in the above bug report. I'll study it tomorrow.