I recently installed Ubuntu on my hp desktop and I've had a lot of problems.
After the initial install I got a lot of screen flicker and it eventually overheated and turned off (when I tried to turn it back on it said it had shut down due to temp). This system has had trouble with overheating back when it ran windows, but only when doing certain activities, and never so soon.
Today I came back and dusted the machine (admittedly I didn't inspect the cpu heatsink because I try not to mess with it if I can help it) and the flicker did happen, so I continued to use it for about 10 minutes to test it and the flicker came back worse than before. It's impossible to look at the screen almost. And it seems to be linked to actions performed, so it is at its worst when moving the mouse, clicking, a page is loading, etc.
I installed psensor to see if I could find out what may be overheating as well, and I see that one of the temps (it doesn't say what it is, just "temp1") is running at just about constantly at 98-99C from startup.
I really need an OS and I'm sort of at a loss as to what to do next, so any help is appreciated.