I've been suffering from this issue almost at every shutdown since I installed Ubuntu (first 12.04 then 12.10), it disappeared when I switched to KDE a couple of weeks ago. The more the system is used, the more likely is the issue to happen, but I was never been able to reproduce it systematically. I have an ATI Radeon HD 3600 and fglrx-legacy 8.97.100.7.
I've been suffering from this issue almost at every shutdown since I installed Ubuntu (first 12.04 then 12.10), it disappeared when I switched to KDE a couple of weeks ago. The more the system is used, the more likely is the issue to happen, but I was never been able to reproduce it systematically. I have an ATI Radeon HD 3600 and fglrx-legacy 8.97.100.7.