I was about to post about this very topic when I saw yours. I have some added information: I also have this problem on a 4 monitor setup (in a square). I found that it works when I change my primary screen to the top left window, and I can repeat the issue when i have my primary as the bottom left screen.
I think there may some sort of error with having a negative window value (only vertically) somewhere, since the top left of the primary screen is 0,0 and anything above that would be a negative y value.
Currently my workaround is to just change my primary screen, but I'd like to have it eventually back to the bottom left as it's a much more natural position for my primary screen to be.
Note: The problem is not specific to a particular skin. I tried 8 different skins, all of which had the same issue. When I switch back to default (basically disabling WindowBlinds) then it begins to work again. I saw a post elsewhere that someone was having some sort of related issue when WindowBlinds was open only, but this seems to not really be related/the same thing. My install is on a fresh copy of Windows 8 just installed (re-formatted and started from scratch), so there are not likely to be compatibility issues causing this error.
Windows 8 Pro
WindowBlinds 8.0 64-bit OS
AMD Catalyst 13.4 Drivers
HD Radeon 7900 Series x 2
Asus VH236 Monitors x 4 (top 2 connected to DVI,bottom 2 connected to HDMI)
