Duplicated POST from IE

Hi, I awould appreciated for someone who can give hint the following problem.

We have a Web-based application powered by IIS and SQL server 2000. On some of our ASP pages, we have a save button to allow the user entered fields to be save to database. The following things occurred on some browsers (IE) ocassionally: one Save button click will cause two records to be saved. We notice from our network trace that when such a scenario occurred, the browser will post the request in the first 7 frames, then reset the connection in frame 8. From frames 9 - 11, a new connection is established via a three way handshake. In frame 12, another request for the same ASP page is posted on another port. Probably this is the reason for the IIS and SQL server process the insert statment.

Does anybody there have similar experience? Is this a known bug in IE/IIS? Any hint on solution for avoiding this?

Your help is greatly appreciated.

Thanks.

Ed