Can't Delete Message in Outbox

Am using Windows mail on a brand new computer running with Vista Home Premium. I sent a mail yesterday that got stuck in my Outbox Folder. It is not getting deleted, neither getting send, nor getting opened. This is the error I get:

"Message could not be displayed
Windows Mail encountered an unexpected problem while displaying this message. Check your computer for low memory or low disk space and try again."

And when I try deleting the same, it says "An unknown error has occurred." This is now becoming very annoying because of just this one message none of my mails are getting sent. Somebody please tell me how can I delete this mail or get rid of it? Thank you.

If you are not able to delete it from Windows Mail Outbox, then better lets try deleting it using Windows Explorer from its store location. To get where is it location, Click Tools on WM and go to Options > Advanced tab > Maintenance button > Store Folders button. This will show you the location, copy the same. Now open windows Explorer and go to that store location. Here click the Outbox folder, locate that following message and delete it.

Hey guys, I found a Microsoft KB Article with exactly the same problem you mentioned above. So I think you should check out the same, it will surely help you.

Messages may be stuck in the Outbox when you use Windows Mail on a computer that is running Windows Vista

Even I started getting the same problem. But fortunately I got to this thread and the tips of deleting mails through windows explorer really worked. Thanks for sharing the same buddy. However this KB articles says to update Vista. Is it really necessary to update entire operating system just because of a mail not getting deleted?