I upgraded to 12.04 several months ago since then I have had many problems that I cannot get to the bottom of!
The first is on boot displays a message from udev then when I am using Ubuntu my Cairo dock gets a black border, then the bar disappears, then one of the windows refuses to close, I then open a terminal to kill the errant program but cannot enter anything in it.
The first time this happened I tried to reload Ubuntu from the 12.04 disk I had downloaded but the disk wouldn't boot into the install nor the live screens, so reloaded Ubuntu from 11.10 disk that I had, I then tried several times to down load the 12.04 disk, with same results. This has happened three times now.
I have loaded two versions of Ubuntu one I have upgraded to version 12.04, and one I have left as version 11.10 to see whether it happens to both or just the 12.04 version.
Has any one else had this or similar problems, and if so what is the solution as I have been unable find one?