Server rebooting due to Symantec Antivirus 8.1.1.323

There are unexpected system shutdowns and After enabling the creation of memory dump files on the server, and
analyzing the first .dmp file generated:
BugCheck 1000008E, {c0000005, 809040be, b4c4a6d4, 0}
*** WARNING: Unable to verify timestamp for NAVAP.sys
*** ERROR: Module load completed but symbols could not be loaded for NAVAP.sys
Probably caused by : NAVAP.sys ( NAVAP+2d873 )
Followup: MachineOwner

We have windows server 2003 and we are using Symantec Antivirus 8.1.1.323.

There are unexpected system shutdowns and After enabling the creation of memory dump files on the server.

This is a virtual server.Host is experiencing unexpected system shutdowns (sourcetype="wineventlog:system" AND EventCode="6008")