When a Backup File has been requested using any of the frequency based options, and the solver is run in parallel mode, the run can crash when the second or subsequent Backup Files are written.
This is due to a bug in the CFX-Solver. The creation of a new Backup File is (by default) followed immediately by the deletion of the previous one. However, the routine which controls this action is called from all processes, not just the master. In some circumstances, therefore, a solver process can attempt to delete a Backup File which no longer exists and so the run crashes.
No workaround is currently available.
ANSYS CFX Release 11.0 Update 1.