When composing a new message, it will not allow a specific user to press
"send". 
a message box pops up and displays "Resource Not Found".  it saves the
message in the Drafts folder.

When replying to a message and the user presses "send" a message box pops up
and displays "The action cant be performed" and saves the message in drafts. 

I have opened the mailbox in question on multiple machines and the problem
follows the mailbox.  I can open other mailboxes in OWA without any problems.

I moved the mailbox to another storage group and the problem follows as well.

Any thoughts?

Fix Outlook Clients Cache Mode
Exchange 2003 and Active Directory Users and Computers.
Multiple people using 1 mailbox HELP !!
OAL (apparently) 0x8004010F
Email rejection