Error in batch run (not distributed) in Simulate 6. "The engine is unable to open the file (null)."

I had a batch run over the weekend where all the runs appear to have failed.  The .pas files include the error message

Begin Contact Pressure Calculations
Fri Aug  2, 2019   17:19:01
*** A fatal error has occurred. ***

The engine is unable to open the file (null).
Please check the directory/file permissions.

Similar error listing in .rpt.  All disks are local except the license server.  The results directory is set for a different disk than the temporary files.  An example of the mechbatch.bat text is

@echo off
 
REM Batch file written from:
REM     Creo Simulate Structure P-60-32 - PTC (tm). 2013
REM Fri Aug  2 11:45:28 2019
 
REM Design Study Name " V13Z43_10_RC_LC_CHC_WB_8th "
 
IF NOT DEFINED PRO_MECH_COMMAND set PRO_MECH_COMMAND="C:\Program Files\PTC\Creo 6.0.1.0\Simulate\bin\simulate.exe" "C:\Program Files\PTC\Creo 6.0.1.0\Simulate\bin\simulate.psf"
IF NOT DEFINED PTC_D_LICENSE_FILE set PTC_D_LICENSE_FILE=7788@svgcfmapp1
call "C:\Program Files\PTC\Creo 6.0.1.0\Common Files\mech\bin\msengine.bat" "V13Z43_10_RC_LC_CHC_WB_8th"  -i "F:\00ProEWorking\LLConn_Ver13A" -w "g:\simulate_temp" -solram 10240   -ascii             -num_threads ALL   -results_io_cache_size 1024      -results_always       -nl_ldc      

Any ideas.

Thanks

SOHS