UPDATE: Have Internet Connection But Email Won't Connect

I run on Windows XP. I have been using Microsoft Outlook Express as my email client. I have never had a connection problem with my email before. A few days ago I started experiencing problems with my email not being able to send or receive. Even though I had an internet connection and all other internet using programs on my computer connect fine. I have checked all of the settings several times in my email program and have verified they are correct.

Here's the interesting thing. I have tried restarting my computer but that doesn't help. However I have also tried restarting my router. I use a Belkin Enhanced Wireless Router with firmware version F6D4230-4_WW_1.00.03. Generally after restarting my router my email will start working properly again but only for a couple hours then it will stop connecting again. I have exhausted what I know trying to fix this and would appreciate some expert advice.

UPDATE: I have tried several different email programs, triple check all settings and no email program will connect. Internet Explorer and Firefox browsers will connect just fine and I can browse with no problems. However I have discovered that the following programs cannot access the internet: Ventrilo, World of Warcraft, Windows Messenger or any other program that uses internet access.

Heres some more information. I have also discovered that this is happening on a second computer on my home network that uses Windows 7. Same exact problem. I also have a third computer on my home network that uses Windows Vista and THAT computer has absolutely NO problems with any program connecting to the internet, including email. I have no idea what to do at this point. I have tried everything I could think of and checked all settings on both computers and on the router.