Problems sending emails with Windows Mail (Vista)

[#1]

I've not been able to send emails for over a week with Windows Mail. My settings are correct and Plusnet Support refreshed my account, all to no avail. Strangely, no error message comes up when I try to send.
Has any other Vista user had similar problems?

[#2]

Are you able to send email using an alternative mail client?

[#3]

Top work Bob
I had the same problem with Windows Mail & have spent the last two weeks trying to get it to work, including uninstalling Norton, etc
Just installed Thunderbird as you suggested and within 2 minutes I was up and running, with no changes to AVG & Firewall.
Nice job