After reading several threads about CryptoLocker today, I decided to try upgrading my AV from Microsoft Security Essentials on both of my machines to the free version of Avast.
It went smoothly on one machine, but caused frequent UI hangs requiring the reset button to be hit on the other.
The biggest differences I can think of between the 2 machine configurations are
a) Haswell vs. Bloomfield and
b) The pooled DrivePool volume mounted as E:, using 4x WD 4TB Red drives which I removed drive letters from so they don't show up in explorer, since you aren't supposed to interact with the file systems on the drives making up the pool directly.
Would this be what is causing the instability when Avast is installed? If so, is there any easy way to get it to ignore drives without letters assigned?
