Seriously. This is exceedingly fucking weird. I can post on TF2maps, but I can't go to any other site besides dropbox. Steam won't sign in, neither will AIM. Haven't tried MSN. I need HELP!
Sounds like a DNS problem. Basically, a DNS is a server which finds the server IP when you try to visit a website. For example, when you go to http://www.tf2maps.net/ this info is sent to the DNS server where it then finds out the IP for that website and uses it to connect.
You should try switching to another DNS. I use OpenDNS and you can find out how to set-up your router or whatever by visiting here here.
If this is your first time logging in after the migration (Feb 8, 2022), you must reset your password to log in. Follow this guide if you're having trouble