Usually I get Mozilla/Firefox Not Responding, and it tends to freeze Outlook as well, if it's open. Once I close the processes through Task Manager, everything's fine.
This time, after I got the tabs open, I clicked on one and it seemed like it was going to be ok, and then both monitors went black except for the arrow cursor. All I could do was move the cursor around, but none of the usual tricks (clicking, space bar, enter, Ctrl-Alt-Del, etc.) did anything. I also couldn't lock the computer. After maybe 10 minutes I did a hard reboot.