I have an older HP Pavilion from 2007 that I have been trying to get up and running. It originally had Ubuntu 13.04, but I was experiencing crashes where the entire screen would turn into corrupted garbage (happened twice when trying to install mp3 codec). I ran a whole health check on the RAM and it passed.
I replaced it with CrunchBang Linux, and it worked fine, but it failed to connect to wireless networks (the previous Ubuntu did). So I decided to get the latest Ubuntu (fresh install). It installed fine, connected to the wireless network fine as well.
It even seemed to boot okay, showing the keyboard shortcuts splash screen. However I could move my mouse all for about half a minute, then it froze. Then after about 10 seconds it unfroze to show my mouse's new position, promptly freezing again. Ad infinitum. I can't do squat.
Each time it updated my mouse's position, it failed to update the clock. It was frozen at 11:01am. It didn't seem like the CPU was doing anything. Also happens again after a restart.
AMD Athlon 64 X2 5200+
On-board GPU roughly equivalent to NVIDIA GeForce 6150SE
Fresh install of 14.04 boots frozen and updates mouse every 10 seconds -- as if CPU is extremely busy and overwhelmed, but never goes back to normal. I can't do anything at all. Ubuntu 13.04 and Crunchbang didn't have this problem.