Outlook 2003 and Auto Reply

I use Outlook 2003 with rules to respond to certain Subject Line Material. I have these setup to reply to common Help Questions coming from people all over the word. All of a sudden the Auto replies quit working and started giving me an alert box that says the message can’t be sent. I have been all over the knowledge base and found nothing. Outlook is setup using POP3 email accounts. I switched back to outlook 2000 and they have be working fine. Looking for any input that anyone can give me.