AccelePort Ras 8 is crashing windows

Recently installed two Acceleport Ras 8 adaptors into a WinNT Server. They installed without issue and have the latest drivers.

Have tried to test the cards with a dialup. The machine used connected fine, but when authentication for full access was started (ie: about 10 seconds after entering my username and password), the server crashed with a Physical Memory Dump. The error code IRQL_NOT_LESS_OR_EQUAL was displayed before the server rebooted.

Anyone seen this before and are able to help?

Cheers