I started an update. It ran for a couple of hours, and was proceeding. I went to bed. When I got up, the update was still running, but had made no progress for 7 hours. I tried to cancel it using the gui, no luck. I then killed the process and rebooted. When I tried to restart the update after the reboot, some flag somewhere is set saying that an update is already running.

What do I do now?

Please let me know what further info is needed, if any. Ubuntu v 12.04 on a Dell Latitude D620 (yes, it's old). Please give paths for any log files that are needed.