Not receiving mail in Thunderbird

Sometime yesterday I quit receiving new messages in Thunderbird. The only thing I downloaded was the Folding at Home client, which I don't think would affect it, since I'm on a network that has a seperate line for email and a seperate line for internet. I restored all my Reg Cleaner backups, and what not, but still nothing. I am able to send email, as far as I know, since no error or message appears that says I'm not sending, but I sent an email to myself and can't receive it.
I'm running XP with Avast, Microsoft Antispyware, on an Athlon 64 machine with 2Gigs RAM and 2 200 G Hard Drives.
Should I just reinstall Thunderbird over the top? Will this repair it without losing all my messages, etc?
Eric

 

Hey Halo.
Well, I sheepishly must admit that I don't have a personal firewall, I use the network one, but I know I've been real stupid to do that.
The pop and smtp settings are still correct. I set up my email account on my daughters computer and checked the mail, and there's plenty of mail coming in, so I know it's something with my machine.
The mail doesn't come in for me or Cindy, no matter who's logged on. We use the same email address.
Yes, Cindy has a Gmail account, I'll try to send her an email and let you know what happens. Thanks for helping me Halo!

 

Yes, it's sending correctly, Cindy received the email in seconds.
When I hit the "check for mail" button in Thunderbird, on the bottom of the screen it says it's connecting: sending login informaiton: There is no new mail on the server. But I know that's not true, since on my daughters computer it's receiving new emails all the time, and I have hers set to leave a copy on the server.

 

Have you changed, installed new extensions/plugins, upgraded, or patched thunderbird on the problem machine lately? Do you use the nightlies? What version of Thunderbird are you using?

Have you tried re-creating your account within Thunderbird? I.E. Remove the account info, then recreating it?