I just started having this problem about 30 minutes ago. I am running Ubuntu 12.04 LTS, and the update manager came up while I was working saying I had important security updates to do with Firefox. I told it to run, but it does that thing where it greys out the window because the system's thinking too hard, and wouldn't work. Eventually, it came up with a box that said there was a system error detected (no idea what), and the CPU was making a weird dah daaah dah sound while doing nothing. I killed the process for update manager, retried it with the same results, restarted the computer twice (each time, it made the noise while logging on and took much longer than it usually does). Update manager still will not work properly, and when I try to run synaptic, it asks me to authenticate but never brings up the window. I have no idea what's going on, but it doesn't sound good. Any ideas?