In reply to Dominicandave:
Well, if they are re-directing you to sites that look like the front page of various web email sites, but aren't actually those sites, and you been putting your password in to a fake site, then your email passwords will have been captured and probably changed by now.
You could try setting up a new login on your computer, as a completely new account, and try connecting to your webmail using that account. But it could be the whole Operating System that is compromised.
So I'd suggest downloading a "Live" linux CD that you can boot your computer from, and get web-access through that, and give that a go.
Try downloading from
http://www.ubuntu.com/download