Windowed mode = explorer explosion

I just upgraded the cpu / mobo / memory of my computer, and since doing so, running guild wars in windowed mode makes 'explorer' hog resources. While guild wars averages at around 50% cpu, explorer takes around 20%.

My computer specs:

Pentium 4 3ghz with a 2mb l2 cache, HT enabled.
Asus p5p800
1 gig ddr400 dual channel memory
gforce 6800 128, overclocked opening all 16 pipes
windows xp pro, sp1 and all the latest updates

the video driver version is 77.77, it happened with 77.30 a well.

This did not happen on my previous cpu /mobo / memory (p4 2.0 ghz, 1 gig pc2100).

While playing gw, the cpu runs at around 140F, at idle, it runs at 120F.

Again, this did not happen until my new build, and it does not happen in full screen mode.

edit: this is a clean windows build, no virii / spyware.

bumping, i still have this problem. DIsabling HT helps some, but explorer still takes 20% on my CPU on average. This only happend in Guildwars while in windowed mode, no other games.

sounds like a fubar'd windows install (or an improperly configured one). what does explorer use when you are just sitting there idling, with nothing but task manager open?

its a clean install, explorer uses no sys proceses while idle, it only happens with GW. It happened pre sp1, with sp1, and now tih sp2 as well.