I just talked to Matthew G via ZA web support and the basic answer I got was reinstall from scratch since you can't remember what tool you used a year ago to remove a previous product but....

A year ago when I got this computer I uninstalled whatever software,
likely Symantec that came with it through Control Panel. I then installed ZA Extreme Security (v10/v11 I can't remember). This was on Windows 8. I have been using v11 for about 1 year now and earlier this week, I upgraded to v12 (while still running Windows 8). Today I upgraded the OS to 8.1 and the system started
to crash with a BSOD of BAD_POOL_CALLER during shutdown/restart. It looks like it is crashing in fwpkclnt.sys and coming from ndis.sys.

Matthew says he can't help because I can't remember the tool I used to uninstall the original software and it may have left stuff over. I don't buy it, the system has worked with v11 for a year and only now with v12 on Window 8.1 does the issue show.

After looking around I found a document that said I had NIS 2012 on the machine when I bought it. I found the cleaning tool on Symantec's site, ran it, rebooted and then tried again. Same issue, the machine BSOD with a BAD_POOL_CALLER. I can provide dumps if necessary.

Any help/suggestions beyond starting from scratch would be appreciated.

- Richard