freeze / lock up when plugging in any USB device

[Cooper Strange]

When I looked into /var/log/messages, these were the last few messages 
there:

Dec 16 20:27:18 localhost pcscd: winscard.c:219:SCardConnect() Reader
E-Gate 0 0 Not Found
Dec 16 20:27:18 localhost last message repeated 9 times
Dec 16 20:27:21 localhost kernel: mtrr: 0xd0000000,0x8000000 overlaps
existing 0xd0000000,0x2000000
Dec 16 20:27:21 localhost last message repeated 2 times
Dec 16 20:27:21 localhost kernel: agpgart: Found an AGP 2.0 compliant
device at 0000:00:00.0.
Dec 16 20:27:21 localhost kernel: agpgart: Putting AGP V2 device at
0000:00:00.0 into 1x mode
Dec 16 20:27:21 localhost kernel: agpgart: Putting AGP V2 device at
0000:01:00.0 into 1x mode
Dec 16 20:27:21 localhost kernel: [drm] Setting GART location based
 on new memory map

I do not now if that helps anybody out there, but it certainly means 
little to me.

One more little tidbit that might be of use to someone in figuring 
this problem out: I had mentioned that I had FC6 running on this very 
same desktop, but reinstalled because I wanted to make more swap 
space. (And no, I did not update so cannot use an old kernel to 
boot.) On the last installation of FC6, the boot up time took ages, 
and I noticed there were a lot of xen messages at the end of the 
booting process. This time, there are none (and boot time is much 
faster). I do not know if xen has anything to do with this issue, but 
it might be helpful to know. Both installations of FC6 I did not 
update, but loaded FC6 fresh, though the first time I used prior disk 
partitioning and the second time I reformatting things.

Some System Info:
AMD Athlon 700 MHz 256KB Cache
512MB RAM
ATI Radeon LE Graphic R100 QD 64 DDR