I use firefox (portable version)
I have tabbed browsing.
Whenever I have an open in a tab on the same window as something else, certain parts of the 'else' don't seem to work right.
for example, I have to close all Amaranthia.com tabs to use Ted.com's home page b/c the links don't want to come up.
Even as I'm typing this, my cursor keeps switching between the text line & the pointer arrow.

EDIT: oh yeah, OS is windows XP if that makes a difference. . .

You sure it's Amaranthia? There's nothing on this site that would cause any weirdness like that.

Done a virus/malware scan lately?

What's the 'portable' version of Firefox?

Does it do it on other sites as well?

http://portableapps.com/apps/internet/firefox_portable
that's the site. They turn different programs into sth that can run off a flash drive.
(if the url gets removed, google 'firefox portable' and it's the first result)

and it happens on all sites (regardless of if in a different tab or window) but only when I have this site open.
It actually seems to be related to having multiple tabs open. On the computer I'm currently using, I have to just go crazy w/ the number of things I'm looking at but other computers, 1 is enough to make it do that.

The computers I'm using are school computers, so they get checked regularly for any kind of malware by our IT department.

Its your computer bub. Not this site. I recommend a scan and a complete reinstall of firefox. Completely uninstall it, delete the folder, THEN reinstall it.

It's not my computer because the same issue happens on about 20 different computers.

Doesnt happen to mine. :/ But I dont use portable

But I do have noscript installed.

Wow, this has never happened to me, but I doubt that it's the site. I don't use the portable version of Firefox, but you should make sure you run a virus scan!