Cannot reply to a certain message

I'll try to explain this as clear as possible.

Yesterday, when I was trying to send a message, I received this error message: "Unable to connect to the network. Check your network connection or modem ". So I thought it was just our internet provider that was having problems and didn't think anything of it. Later on in the evening, I was able to send and receive messages alright and thought it was working again. However, today, after having restarted the computer, I went to that same message I was trying to reply to yesterday and received the same error message. After testing things out a bit, I have now found out that this only happens when I reply directly to that one certain message while anything else, (composing a new message, replying to a different message, etc..) will send. What could the problem be with that one particular message and why won't it send? Or should I just be satisfied that it works for all other messages and not be bugged by this little error?

By the way, I'm using Microsoft Outlook 2003 (11.8217.8221) SP3.

 

AHHH... well, now none of my messages are being sent. Not even your suggestion worked, Steve, thanks, by the way. I am getting that same error. And I'm not able to delete them from Outbox either. I'm able to receive messages alright, though.

I think it's time for a break with chocolate now before I go crazy...