It's not exactly the same thing, but I have seen MS Office apps hang when the PC client loses connectivity to a share. It happened very predictably, even if the file that was opened wasn't saved on the share. If Outlook was running, the entire PC would just hang.
It was caused by a bad NIC on the samba server and the hanging would last for longer periods of time as the card got flakier.
Did restarting samba before the reboot change anything?