NIS 2011: Random BSOD on system shutdown- SRTSP64.SYS

I recently switched my Windows 7 x64 Professional from Avira Premium Security Suite V10 back to NIS 2011 V18.5.0.125.  My Win 7 x86 Professional computers are on NIS 2011 and I figured I just make everything standard across the board.  I thoroughly removed Avira...registry cleaning, etc.  Since installing NIS 2011 on the 64-bit system, I randomly get a BSOD on system shutdown.  It references SRTSP64.sys as the culprit.  The BSOD does not occur except at shutdown.  And the BSOD does not occur on every shutdown....like every 10-15th shutdown.

 

This is on a Dell XPS 410 with 8 gbytes RAM, dual WD VelociRaptor 300 gbyte hard drives, Creative X-FI ExtremeMusic sound card,  nVidia 8800 GTX graphics, dual Dell U2410/2407 WFP monitors, Intel Core E6700 2.66 GHZ processor, cable modem.  All hardware drivers are at the latest versions. 

 

I have gone through the process of uninstalling NIS, using the Symantec Removal Tool, and re-installing with no success in resolving.   I've tested memory, run chkdsk, and am showing no hardware issues.  System runs without issues on Avira. 

 

Attached is the minidump.  I also have a 288 megabyte zipped memory dump if it would help to resolve.