Sounds like the same exact thing that happened to me, and it turned out to
be a spyware hijacking by coolwebsearch.
The first thing you need to do is check your system for Spyware, go get
Spybot or any one of the many others, and run it.
The first step is to find out what you got, and then deal with it.
But your symptoms sound a lot like mine were
IE Scrolling is very slow, jittery, sluggish even on a DSL.
Long delay when trying to highlight text on a web page.
Long delay when typing text into fields on web pages.
IE delays when closing up to 30 seconds or more
ZoneAlarm keeps telling you Coolweb???.exe wants to access the net.
Here are the links once again to learn more.
http://www.spywareinfo.com/~merijn/cwschronicles.html
http://mvps.org/winhelp2002/unwanted.htm
GRiZ
..
Everything downloads at the same speed, but scrolling down
is extremely slow, and entering text, eg into search
engines, takes ages to appear.
Help!