Glad to hear it!
You don't need to restart your computer as you add them back, just your browser. As for how it gets attached, I'm not well-versed in the specifics, but generally any plugin/add-on you install runs this risk, so always make sure you can trust the source. Some software also has "sleeper" periods, where you'll install it, it works fine for a month or two, and then it triggers the adware to start popping up all of a sudden - the idea being that you wouldn't suspect the plugin of being the culprit since it was installed so long ago and never caused problems before.
As for why it seems to trigger more on this site than others, I really don't know - I guess we're lucky. :-)
Also - if you have the list of disabled plugins, try googling each one by title and see if anything pops up about others having similar problems with it. That might help you narrow it down.