still having pc trouble switching clients running multiple instances of the game

I recently had to wipe my comp to clean it, and restored it to it's factory settings after that nasty AV Security 2012 virus, I removed it and restored my comp's settings back to factory settings, and I usually run multiple accounts on my Dell XPS Studio desktop, and I had no latency problems when I would alt/tab to switch my boxes to multi-task, which was a long time ago, but I believe I did something to the settings of my computer.....but can't remember... that allowed it to do so, but now when I try to alt/tab to switch my boxes there's a brief pause of latency everytime i press the windows key, along with sometimes when I hit the key to open the start menu to launch other game clients, there's rainbow colored lines every now and then, and also there will be a severe pause of latency, anyone have any ideas as to how to fix this problem?!?!

It sounds like you're running fullscreen, which has always been flaky. Can you tolerate running in windowed mode? I frequently run two accounts windowed and it works fine. (I do use /maxinactivefps 5.)

I'm not sure what your specs are, but using the mentioned "-maxinactivefps 5" under the launcher settings seems to help when using the Win+Tab/Alt+Tab function in full screen mode. You may need to lower your graphics a little ingame though if you notice the game gets laggy or (like my old machine) ends up turning everything but the UI black after toggling. A good 'test' would be to set the launcher to Safe mode and see how it handles two instances. If it handles that fine, then slowly slide up your gfx from lowest until it's as unstable as you care to deal with.

BTW: that FakeAV's a P.I.T.A. isn't it >.<