I have the same problem with Win 7 HP 64. I can't reproduce yet, but I use in 3 environments since it is a laptop.
- Office 1 - 2 External monitors - 1920x1080, and 1280x1024
- Office 2 - 2 External monitors - both 1920x1080
- Laptop mode
The problem only occurs in scenario 2. It somewhat seems to be related with using Office Communicator to share desktops, but I am not convinced of that yet.
In addition to the cursor turning to a half fishbone (which usually resolves itself pretty quickly), typically sometime after that (sometimes an hour later), both displays go blank, internal fan goes to 100% speed, and computer just hangs.
I found some discussion of others with similar problems at the following (had to use cached version of page since the link didn't work for me):
http:\social.technet.microsoft.com\Forums\en%2Fw7itproui%2Fthread%2F820764ce-97f6-49e6-9735-014531664e0d&ei=CESET6LkKoei8QTF48XCCA&usg=AFQjCNE6SfT7KOlXiao6I9q_Ln1SaIxbvA
Cached version:
http://webcache.googleusercontent.com/search?q=cache:tWY-orpDMbMJ:social.technet.microsoft.com/Forums/en/w7itproui/thread/820764ce-97f6-49e6-9735-014531664e0d+&cd=6&hl=en&ct=clnk&gl=us
basically, they were saying it was a ATI driver problem. I do have the "AIT Mobilitiy Radeon HD 3400 series" driver.