freeze / lock up when plugging in any USB device

[Cooper Strange]

When I plug in any USB device (USB thumb drive, external hard drive, 
etc), everything freezes up: mouse and keyboard are totally 
unresponsive. I did not have this problem on a previous install of 
FC6 on the same computer. Trick is, I cannot use the computer at all, 
because all my files are archived on my USB external hard drive.

I have already loaded FC6 on my desktop before, had used the previous 
partitioning scheme from FC5 (preserving /home without formatting). 
Since I had added RAM in the meantime, I wanted to go and reinstall 
to make the SWAP space bigger. When I tried to use the computer again 
after reinstalling FC6, I ran into the USB freeze up problem. The 
computer is running on an old AMD processor.

I searched through the list archives and listed bugs, but did not see 
any information that sounded right. One bug did have to do with USB, 
but that seemed to be a problem of the device not being recognized. 
Mine just locks up the computer.