Please raise a service request on this, and someone with specific Modelsim knowledge will be able to assist you.
I'm no longer under a service contract. I simply don't understand why it crashes most of the time after a simulation has started. Very infrequently it will simulate once, but crashes upon a "restart" command . Almost every time it crashes immediately after the vsim command is executed. Completely unusable. Our licence is good. We purchased a permanent license.