Constant Freeze/Crashing While Running Virus Scan

Every time i run my Webroot Spysweeper with Virus Scan (used this program for years) i get a system hang/freeze every time the scan gets to the file
SysWOW64/ntdll.dll
It freezes at that file constantly....nothing happens cant move mouse cant use keyboard cant use anything, have to reboot pc via the restart button

What can be causing this? i tried reinstalling the virus program (this is a relatively new PC build....however i have had scans run fine in the past so id love to know what the issue is?) only thing i can MAYBE think of is i havent run a scan since switching GPUs i switched from a 9800GTX+ to a XFX 6850 but I did all the necessary things to swap drivers from nvidia to ATI

x64 bit system
This is the original Install on the System
OEM version when i ordered computer
System is under 2 months old as is the OS

but with a clean boot my virus scanner wont start.....

ok so i did a cleanboot and ONLY put in the AV program in the cleanboot and it still locked up when doing a scan....it locked up on a diff file svchost

this leads me to believe it is the AV program itself?

i just fully uninstalled the AV and am going to reinstall it and see what happens

u got any problems tho gaming with MSE constantly needing permissions and such?

i liked Webroot cuz it had gamer mode and such and u only had to add a game once to a permission not every time

and how/where can i get MSE?