I have an issue when I access the application, I notice that Page_PreRender is fired twice. This only happens the first time in a new session. It does not happen if I refresh the page, or on postbacks. I use .NET framework 3.5 and the built in ajax functionality.

I think the problem is not related to img tag with empty src attribute as I have seen other posts has mentioned, because I see this in both FireFox and IE. The posts I saw about this stated that this was not a problem in IE. I have also searched and found no img tags with empty src in the generated page source, so it should not be this.

I have also made a simple test page where I have included some of the functionality, and this does not happen. Here I have also tried to reproduce the empty src bug by including <img src="" /> on the page, but this does not trigger this problem.

Have anyone any suggestions on what happens? Note: It is the entire page cycle that is firing twice, not just render.