Abaqus Standard / Error Message

Hello All,

I submitted a Abaqus standard job via A/Command (interactive), and the following error message was reported in A/Command:

*** Error: abaqusstd.exe / rank 0 / thread 0 encountered an unhandled exception

*** ERROR CATEGORY: ELEMENT LOOP

The message file states:

---------- RUNTIME EXCEPTION HAS OCCURRED ----------
*** ERROR: abaqusstd.exe / rank 0 / thread 0 encountered an unhandled exception

No other error messages or additional error information is in the .dat, .msg, or .sta files. 

Does anyone know what this might be? Have never encountered before. 

Thanks in advance.