It seems you have been victim of this Heisenbug(1):
If it is it, a workaround is to issue
sudo modprobe wacom
before connecting the tablet. After doing that, you should have the driver loaded; check it with
lsmod | grep wacom
if you have an output like
[romano:~] 127 % lsmod | grep wacom
wacom 62856 0
Then the driver has been loaded. If you are suffering this bug, now you can plug the tablet without problem. If your computer still crashes, you are facing another bug.
(1) It is a strange bug, because I was not able to reproduce it at will. For me it disappeared after upgrading the kernel and/or when I installed a locally compiled driver as explained here.