Mac Mail -- Can't move mail to folders

I'm running Mail 3.5 on Mac OS X 10.5.5 on a Mac Pro.

I have an IMAP account for my business.

My problem (which recently developed) is that when I try to move individual messages from my inbox to a folder on my local machine (a) the mail won't "stay" in my local folder and (b) the mail reappears in my inbox.

The result is that I can neither keep my inbox clean, nor archive messages by client in folders on my hard drive.

I created the folders on my hard drive when I was running a POP account -- I switched to IMAP when I got my iPhone last summer. But this problem started long after that.

Any suggestions?

Thank you

Can't move mail to folders

Hi,
I'm on IMAP too and have been experiencing this problem for few weeks now. I have limited space (as we all do) and not being able to move messages from the server to my local HD is a problem. Did anyone find a solution?