Well there was a huge amount of changes from rc1 to rc2 and just a few from rc2 to rc3.
You more than likely have a hardware issue that may or may not be fixable.
Go to the bug tracker and search there first. There have been quite a few hardware related bugs and some have a fix or work-around.
If you can't resolve it with existing suggestions then raise a new bug and be prepared to be very specific about your exact hardware setup. Not just make and model number but everything from memory, hard drives, nic cards, everything down to what kind of raid card is in it.
Then be prepared to supply every bit of information you can capture before the hang up.