Xvision, X Server, FEFLOW 5.2, PEST, crash

I'm trying to resolve an issue and could use some advice ASAP.  I use an older version of FEFLOW (v5.2) and I'm having the Xvision crash while FEFLOW opens the display 'localhost:10'. 

1. I'm using PEST (v12) in regularisation mode with FEFLOW.  So PEST process calls FEFLOW numerous times during optimization process.
2. I can run one optimization of PEST without incident.  During the second optimization routine, FEFLOW crashes (as noted above).
3. If I kill the 'xservice.exe' file in the Windows Task Manager, the routine will then continue but only briefly - when PEST and FEFLOW both crash.

This must be a X server issue.  So, how can I overcome this?  Is there an open source X server (e.g., Xming or cygwin/X) application that I can use instead of X Vision?  Anyone have experience with using these?

Thanks!

Okay....  I may have overcome the issue.  I uninstalled AVG software and things seem to be working better.  Although, XVision still hangs up and I have to restart it.  But now when I do that, PEST and FEFLOW continue on their merry way.