Freezing on slave issue

I've just started 4-boxing, and I'm getting some odd behavior in that 1-2 windows will randomly stop accepting input .. they aren't frozen but they won't accept mouse of keyboard input. I can click away from them to one of the working active windows and those are fine, but the locked windows will stay that way for a good 10-20 seconds at a time, at least. I read a few others having similiar problems but couldn't find a solution that pertained to my situation.

If I didn't know better I'd think I was overloading my system, but I checked CPU and memory usage neither seem to be pegged.

I'm using ISBoxer.

My admittedly weak system specs:

AMD 3800 (Dual 2.0)
3 GB Ram
9800GTX+
WinXP Pro

1) Would I see a significant difference upgrading to 4GB and a quad core (likely a Phenom)?
2) Anyone experience the 1-2 window lockup / find a solution to this?

you would find a huge uprade in proformance in the quad core and 4 gigs, BUT

I am not sure where you are, but my computer is somewhat like urs (was), and I was smooth rolling 4 up to 70 till i hit northrend where it was a little choopy but it was smooth, just not visiaully pleasing, but then dalaran and bg's and bigger questing areas came, and they just died/froze up. I woudl truely want you to consider throwing down like 400-1000 bucks to make ur system run really really fast even in dalaran and BG's when you hit 80

Hears what Im talking about

Intel 920 CPU
intel extreme motherboard
12GB or DDR3 corsair memory
a at 1GB memory video card
some cooling for this awsome rig
750+ watt power supply
=
900-1100 bucks
=
some insane proformance

I am not sure about ur budget, but if you plan on arena and all that I would do this, but if not maybe some small upgrades just to make the whole process managable

I do not have a problem with the locking up, but sometimes 1 of my 4 characters do not recive the keypress, but all i do is just press it 2 times and it gets it.. maybe just like server lag or something i dunno.. or out of range.

As in... you press a key... and your main receives it.
You have 3 slaves, 2 receive the input but the third does not.
You press the key again, and now all of them have the input?

It is weird that some receive it while others do not.

I've noticed its rather easy to open a chat window on one or more clients.
And chat windows eat keystrokes...
But that's probably not your issue, if they get the command on the second press.

Perplexing.

Thanks for the assistance, and your thoughts on this...you folks are very helpful, and I appreciate it!

After trying a TON of different adjustments, I realized it's a maddeningly simple issue.

I'm using ISBoxer, which has a feature that allows you to switch screens with no pause. When I switch screens, however, is when the input lockout occurs. I've stopped using this feature, and all is well.