Hi, welcome to DUC.
First: please try searching for past threads before posting. You can almost always solve Pro Tools ASSERT error by careful searching for past posts here or in the Internet. The line numbers in the error message may change but the causes are usually the same.
See if this helps, are your running accounts off a network?
http://duc.avid.com/showthread.php?t=383903
If you still have a problem...
Post a Sandra report for your system. See under "Help Us Help You" up the top of each DUC web page.
What playback engine are you trying to use?