Use the Microsoft fix:
http://support.microsoft.com/default.aspx/kb/941090
"Messages may be stuck in the Outbox when you use Windows Mail on a
computer that is running Windows Vista"
That page offers two download options. Unless you know for sure
you have 64-bit Vista, use the 32-bit option.
Also, although only the outbox is mentioned, it works for all stuck
emails regardless of which folder they are in.
--
Gary VanderMolen [MS-MVP WLM]
"April" <April@discussions.microsoft.com> wrote in message news

C15948B-A8D0-4E2E-B6C3-FD10BE148A14@microsoft.com...
>I have been having the same problem. I can't delete mail out of my inbox.
> If amyone can help I would really appreciate it.
>
> Thank You
>
> ayoung002@new.rr.com
>
> "Ronnie" wrote:
>
>> Message says " an unknown error has occurred.
>> Please advise on how to correct this problem. Am using a new Dell computer
>> with the Windows Vista, Home Edition"
>> Thanks
>> --
>> ronniej@charter.net