mental ray has been working fine. then i was trying to do an amibient occlusion render and it comes up with this error

// Error: (Mayatomr) : unexpected internal exception during scene rendering, please report //
// Error: (Mayatomr) : unexpected internal exception during scene cleanup, please report //
// Info (Mayatomr): Aborted //

and then it wont render anything at all....

can anyone help please!!?!