Since upgrading, my guests have been completely locking up during "Found New Hardware", in one case it was Nokia PC Suite drivers when my phone got attached, and second case just now, device manager found "Ethernet Controller" which is the Paravirtualised network adapter. Since the upgrade, the Paravirtualized network has been causing problems such as cable unplugged (when it is). I found a few other minor things to be causing problems, such as going to "Shared Folders" while the VM is running, and trying to access some settings before the settings are loaded (before the progress bar disappears), the dialog locked up on me a couple of times.
Hmm.