More info: There are Alerts in my Windows Event Viewer. Here's one:
Faulting application 00839811.exe, version 1.5.1.16, faulting module 00839811.exe, version 1.5.1.16, fault address 0x00004a12.
For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.
Also:
Faulting application spybotsd.exe, version 1.5.1.16, faulting module spybotsd.exe, version 1.5.1.16, fault address 0x00004a12.
For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.
One of the two anti-virus scans was clean - waiting for Avast to finish (always takes a while).
Any thoughts before I re-boot?