Many others are having the same problem. It has nothing to do with the Aquarium. It is a problem with Windows XP Service Pack 2 and the Auto Update feature.
http://www.wsus.info/forums/index.php?showtopic=3830
The computer isn't actually dead/frozen by the way, it's just hung up. If you wait 5 minutes, the computer will unfreeze. Not what I call an ideal situation though.
The easiest solution is to disable Windows AutoUpdate. Make sure it's disabled not only in Security/Firewall but also in the Services admin control panel (Control Panels -> Administrative Tools -> Services).
If you are running Norton Internet Security, add an Exclusion for the SQL log files folder generated by Auto Update.
Days like these I'm glad I stuck with Windows 2000.