Can't delete mail. "An unknown error has occurred" message.

When I try to delete, it comes up with 'an unknown error has occurred'.  It pops up everytime I open Windows Live Mail, for months I've been trying to get rid of it.

Moved from feedback

Split from:

http://answers.microsoft.com/en-us/windows/forum/windows_other-ecoms/why-cant-i-delete-unwanted-mail-it-keeps-coming-up/85e11dd3-4277-4ef7-b9ad-9f2b981e33e1