This problem is most likely caused by your antivirus program.
Windows Mail is not compatible with most McAfee or Norton
security programs. Those will need to be uninstalled.
Replace with a more compatible antivirus like the free Avast: http://www.avast.com/eng/avast_4_home.html
If after you have uninstalled your antivirus, your mail login
still does not work, remove that account, then create it from
scratch. Incompatible antivirus products often corrupt the
password store.
