Frame + Server.Transfert Weird bug

[Simon]

Hello,

I have an ASP.NET site using C#. I work with frames : One
top, left and center (bottom right). When, in the center, I push on a
datagrid button, the page transfert me to another page in the center.

I use Server.Transfer("pagename.aspx");...
The problem is that when I push the button, when the transfer is done,
a little frame between the top and center appear, in blank with
non-formatted text and I see the content of the <title> property on
the center page... Is there anyone who can say me why, or at least if
anyone got this problem before?

Thanks,
Simon