ACCESS_VIOLATION in 3D but not 2D

Brian

I have a simple UDF that works great in 2-D. It's esentially a source term that sways a box to simulate sloshing in 2 directions. Things work great until I try to apply it to a 3D case. I follow all the same steps but with a 3D domain and as soon as I try to run it, it crashes:

Updating solution at time level N... done. iter continuity x-velocity y-velocity z-velocity time/iter

Error: FLUENT received fatal signal (ACCESS_VIOLATION) 1. Note exact events leading to error. 2. Save case/data under new name. 3. Exit program and restart to continue. 4. Report error to your distributor. Error Object: ()

Any ideas?!?