That looks like only part of an error message. If you need more help, click
on the error message and see if you can copy it. Also tell us what if any
antivirus programs you have.
First, however, download and install this temporary fix, with Windows
Mail not running:
http://support.microsoft.com/default.aspx/kb/941090
Although it's labelled as for mail stuck in the Outbox, it also works in
other folders. If you don't know whether to use the 32-bit version or
the 64-bit version, try the 32-bit version first. Certain common
antivirus programs, such as most of those from Norton or McAfee,
tend to cause this and other problems in Windows Mail, although
seldom immediately, so if you have such a program, remember
where to find the fix and hope it will install again if you need it again.
A recent version of the Trend antivirus program also causes
assorted problems in Windows Mail.