Postback stops working after file upload in IE

I have a strange problem with my uploader. My uploader has an file upload control, and once a file been uploaded, the user clicks on a button, and that will insert the image into my editor. The button has onclient click command as:
btnInsert.OnClientClick = "javascript:SelectFile('" + ConfigurationManager.AppSettings["LibraryPath"].ToString() + dtr["filename"].ToString() + "');";
and the script is:
function SelectFile( fileUrl )
{
    // window.opener.SetUrl( url, width, height, alt);
    window.opener.SetUrl( fileUrl ) ;
    window.close() ;
}
That inserts the image into it just fine. But after that, all controls on the page just stopped posting back. I click on save button just does nothing. Nothing happens. This happens only in IE7, it's working fine for Firefox. Does anyone know why? I have to close IE, and re-open it and try again. If ...