Something weird is going on with my Outlook 2007.

After I have new email composed and hit “Send/Receive” button the status
quickly display a “Sending a message 4/4” message.

Why it says that it had sent 4 messages instead of one (I am absolutely sure
that it has no other messages in the queue and only one message added to
“Send” folder after the whole thing)?

I have a suspicion that may be some malware on my PC using outlook to send
emails and to conceal its presence it only does that when I and sending mine.
I checked my PC for any viruses and spyware and found nothing.

Any ideas of what it could be?

Thank you.