A quick update: I just tested it under Arch and I cannot reproduce it there!
This means, that indeed Ubuntu is the problem, for whatever reason.
Well, it is time to leave this ship anyway.
I’m glad to hear you resolved this issue, and that you are still able to work with your current hardware. Apologies for my mistaken analysis regarding your hardware. 
I’ve really had it with ubuntu personally, for me, it has always been a great source of headaches and sort of handicapped me initially because instead of learning linux I was learning all of ubuntu’s funky nuances. I am confident you will be extremely happy with Arch. Their documentation is spectacular and using it as a reference, it has helped me with problems almost every linux distribution.
cheers
stick your own desktop. openbox + bmpanel2 + dcompmgr is enough for the need of speed.
no more bloat in my computer 