Having the same problem here, I do not swap at all. I found windows 7 to be much more faster than any other OS when multiboxing with wow. I can get a good 12 or 20 minutes work of playtime with keyclone working, then boom the window disappears and the only way to remedy it is to quit all the wow clients, search for keyclone in the processes and quit it.

What is interesting though is, I 4 boxed on my macbook pro using it (4GB ram, 2.4 C2D, Windows 7 build 7000) and I never ran into any issues of this sort, so obviously I am doing something a bit different on my desktop.

Specs: Mac Pro Nahelem, 12 GB memory, 2x 2.93 Octad, Radeon HD 4870 X2 + Radeon HD 4870 Mac Edition running windows 7 build 7000 beta.

I am going to fiddle with some options to see if I can get it working stable again.