mm, just some suggestions
One thing I would do is view your tcp-ip status...
if the icon is in the system tray, right click it and then click (status)
then look as see if you have more packets going out than you do coming in when you click a link of something in IE...
Another would be to delete all activeX components installed under this users name in the IE settings.
IE tool bar - Tools - Internet Options - (Temp Internet Files section on first window) Settings - View Objects and then right click each one and view the version info...
Mine has IBM Access Support, acpRunner Class, the Java Runtime 1.4.1_01, Office Update Install Engine, Shockware Flash Object and Symantic RuFSI Registy Information Class... there things are a constant and should be there on my system, if for any reason IE flakes out and a simple restoring defaults does not work, I check here and almost always find something in there that is new and I delete it, seems to fix the problems 90 % of the time...
I would also consider the following for sanities sake
Iarsn System Software: download TaskInfo2003 demo and install it...
http://www.iarsn.com
It will tell you about everything that is running on your system. I would venture to bet that something is opening a thread in/under the IExplorer process and is transfering something or is bleeding all over your systems memory and cpu resources.