Windows 7: Cisco NAC causing system instability

Approximately one week ago my computer began to behave erratically. More often than not (perhaps 80% of the time), the very first time an application that accesses the internet is opened (be it a web browser or an application that automatically checks for updates) the system effectively freezes, forcing me to reboot using the power button. (The application itself remains in a loading state indefinitely, all other applications, task manager included, are unresponsive and/or send back an error message) If I am lucky enough to get past that first hurdle, the system appears to be fine from then on, at least until the computer is next turned off.

This began to occur shortly after my university forced me to install Cisco NAC, a program that prevents unauthorized access to the local net, and Symantec Endpoint, an antivirus program I'm not particularly impressed with. (Previous antivirus was AVG, which was fully uninstalled before opening the Symantec installation file.)

I have already re-installed both programs with no change in behavior and am currently contemplating a full OS install. Unfortunately, I cannot at present definitively confirm whether or not Cisco is the culprit, since all networks I can currently access deny any systems where that program is not active.



Currently looking for any insight as to what precisely the issue may be, new things to check, and/or what can be done to resolve this.