Issue tabbing into World of Warcraft

Hello, friends.
I was just wondering if you've any idea as to why I'm in this predicament; every time I want to tab into World of Warcraft on my notebook with Windows 7 x64 installed, it takes quite a while. Tabbing out of the game is fast, and if I play in windowed mode, both tabbing in and out is fast. It's only when I want to tab in again that it takes a while. We're not talking mere seconds here; sometimes it takes a minute. I don't want to play in windowed mode, however, as I see some FPS drop if I do, so this is an annoying problem.
Also, the time it takes to tab in varies rather much. Sometimes it's a few seconds, and sometimes a minute, like I mentioned before. There seems to be no connection between the "delay" and the, how should I put this, demands on the computer by the game. I can stay in a cottage far away from everything where I have 120 FPS and it can still take a minute to tab in. And sometimes, in an instance, it's instantenous. Weird; makes no sense to me.
Obviously, I downloaded the latest video drivers from nVidia (got a Geforce GT 120M with 1GB vram), and it didn't help at all, and so here I am. The computer appears to work splendidly in all other regards, being fast and lovely etc. It's an ASUS X70IO notebook, with 17,3'' display, if that helps your assessment. Could it be that I somehow installed W7 wrongly? Is there some other driver that I need to install/update? I am clueless and will be very grateful for any adice you can give me.

Thanks in advance,
Ilùvhîr

 

And how do I solve this? Any ideas?
I've a friend who's using W7 as well, and he's got no problem with anything like this, neither on his stationary computer nor on his laptop.
Is it a hardware problem, then?

Thanks