not sure if the box I was having problems with was 0wned or not, but I've seen something like that happen when you use a not so intelligent software firewall and unusual network configuration. for example, having two routers hooked up together (one being set in switch mode) can cause firewalls to silently block all or more mind-bogglingly just some web requests. in my case when I dug deeper I found the firewall was logging some sort of ICMP based attack. i didn't have much luck with tweaking either of the two firewalls I tried and ended up having to uninstall them.

i had tried using Sygate Personal Firewall which while old and probably no longer very secure, it was pretty nice. i had also tried Sunbelt which was thoroughly overcomplicated and not fine grain enough for ignoring specific false positives. the symptoms I saw were the "internet" was not working (YahooMail not authenticating OR the actual emails not opening) while most of everything else worked, except when it was everything that actually would not work.

One hack of a solution for Windows XP/2000 is to use a mouse tray application like Labtec Mouse V2.1. Make sure the wheel mode is set to enhanced scroll mode and you get very good scrolling based on where the mouse is floating.

It won't work without administrator privileges unfortunately, so i have a shortcut in my start up folder and set the shortcut to run with alternate credentials. You might also get some weird interactions with other mouse software, which may take some work to resolve.

I only wish knew a way to get the same effect without using an application, or at least not a tray application to do it. In the mean time, this hack is a god send for me at least.