Help Required.. Tanner TSpice Simulator giving a fatal error

Hi,
I use Tanner TSpice to simulate my circuits and I ve been getting an
Error Msg tht says Fatal Error: Unhandled Exception and the Simulation
is stops running.Nothing is mentioned in the Output file. Each and
every module in the ckt works fine when simulated individually.
Something is killing the simulation and nothing is mentioned in the
output log. Is there anyway I can find out what tht error is and where
it is occuring.

Thanks,
P.S