Lately I've been getting an Application Error message a few seconds after closing out of Revit 2009. It has the red "X" symbol (typical Windows error message) and reads:

The instruction at "0x0114ef7a" referenced memory at "0x00000020". The memory could not be "read".
Click on OK to terminate the program.

Looks like what happens when you do something that causes the machine to run out of memory. However this is AFTER I've already closed the program.

Any ideas? I'm on a quad-core machine with 4 GB RAM.