Odd issue with Win 7?

I'm not sure if this is the right forum, but anyway, here goes.

I'm running five clients on one PC. My system is pretty up-to-date and 95% of the time it's running smoothly, even in Dalaran. Anyway, once in a while this odd thing happens where my main client will slow to a crawl - we're talking 5-8 FPS, both in cities and in the terrain with noone around. If I press ctrl + alt + del, and tab back in, the problem will immediately stop, but if I don't do the ctrl + alt + del, the main client will continue at the 5-8 FPS until I do.

There seems to be no excessive processor or RAM activity during the "crawl" stage - has this happened to any of you guys?

Just guessing, so don't get upset if I am totally off. What if a message wants to pop up and tell you anti-virus is updated, or a new java version is available, then mabye, the main window gets pissed and doesn't have main focus or something. When you leave that window and come back to it, it has the computer's full attention and it works normal.

I had the same thought, so I disabled everything from AV to java updates - only the absolute bare necessities are still running (I even stopped a bunch of Win7 services), but it doesn't seem to make much of a difference :|

Oh, and oddly enough, it doesn't happen in instances, so it may be wow-related, but it does it when disabling all add-ons as well, so I don't think it's add-on related.

I think I solved the problem - for anyone who might be having a similar issue, I'll post the solution:

My processAffinityMask was set to 15 (distribute load over 4 processors) - I simply changed it to 255 (i7 with HT) which solved the problem. My old quad core (q6600) liked the 15 setting, but i guess my i7 likes 255 because of the hyperthreading. Anyway, problem solved and I'm happy - getting good great frame rates :-)