Turn off email scanning of your antivirus software. See
www.oehelp.com/OETips.aspx#3
If that doesn't work then try this:
1. Go to the Vista start menu and type cmd
2. The search results will display a program titled cmd
3. Right-click on the link and select "Run as administrator"
4. type "netsh interface tcp set global autotuning=disabled" without
the quotatioin marks
5. Test your POP account and see if you can now download your mail.
6. If nothing changes, reenable the autotuning feature by typing
"netsh interface tcp set global autotuning=normal"
steve