I seem to have developed a problem with sending messages ...

Every so often, seemingly randomly, I compose a message and send it in the
normal way only to observe it sitting in the Outbox whilst Outlook attempts
to send it. This continues for a few minutes and then I receive an
undeliverable message:

The following recipient(s) could not be reached:

' on 22/11/2007 22:44

451 4.3.0 Error: queue file write error

XXX YYY on 22/11/2007 22:44

451 4.3.0 Error: queue file write error

Any help would be appreciated.

Thanks.