Not sure why all that would be very important.
The type of computer and the OS aren’t especially relevant, particularly considering that we already know the OP is using Thunderbird. Whatever OS it’s running on, the email client needs to do some basic things in order to receive email. The POP (or IMAP) and SMTP settings need to be configured correctly, and the other password and username information needs to be accurate.
But none of those things really change from system to system. Hell, they don’t even change very much from email client to email client. If you know how to set up your account in Thunderbird, you can probably also figure out how to set up Outlook or Eudora or whatever too.
I’m also having trouble understanding why the OP’s ISP is an issue. We’ve already been told that the mail is going through a university mail system, so presumably the email client will (or should) be configured with the POP and SMTP settings appropriate for the school’s mail system.
This is certainly a possibility. If you’ve changed any of your Thunderbird account settings, that could be a problem.
How do you know he hasn’t?
I just looked in that thread, and there’s nothing about setting up email clients. In fact, the whole thread is really devoted to security-related issues such as viruses, trojans, spyware, and other malware.
To the OP:
One possibility is that your school’s IT people have changed the email settings on the mail server. Just last week, my own university migrated all email accounts to a new server, and as a consequence we had to change our POP and SMTP server information in our email clients. But a good IT department should have notified you beforehand of the changes, so if you haven’t heard from them this probably isn’t the problem.
It’s still a good idea, though, to go into your account settings and make sure that the POP and IMAP settings are correct, and that your username and password are entered correctly. Check them against the addresses given by your school’s IT department. Also check that your security settings are correct. After our recent migration, we were required to have our SMTP security set to TLS; if this wasn’t done, the server rejected outgoing emails.
Another possibility is that your password may have expired. I know that, at my school, we are required to go into our accounts (via a web interface) and change our passwords every so often. After a certain period of time (i think 6 months) the password expires. But this also seems unlikely, because if you can receive emails then the server must be recognizing your password.