DAMNIT!

//Error "Fatal (mental ray): mental ray encountered a fatal error. The system may have become unstable. Please save scene and exit maya.

In the mental ray output window....

mental ray for Maya 10.0
mental ray: version 3.7.1.26, Jul 30 2008, revision 26576
mental ray: got 8 satellite CPUs.
MSG 0.3 error 011105: cannot start thread 4: Not enough storage is available to process this command.
MSG 0.3 error 011105: cannot start thread 5: Not enough storage is available to process this command.
MSG 0.3 error 011105: cannot start thread 6: Not enough storage is available to process this command.
mental ray: out of memory
mental ray: out of memory
mental ray: out of memory
mental ray: out of memory
mental ray: out of memory
mental ray: out of memory
MEM 0.3 fatal 031008: can't allocate 1966776 bytes.
MEM 0.3 fatal 031008: can't allocate 1966776 bytes.