open excel html file from codebehind

I want to do something like

Response.Redirect("file://///Myserver/somedir/myexcelhtml.html");

I've tried dozens of things, but nothing works. I've also tried to inject a javascript with a window.open("file://///Myserver/somedir/myexcelhtml.html");

But nothing seems to work. How can this be done?

The file name (and path) is generated just before the Response.Redirect() or whatever it'll end up be is called, and will vary for each call.

Please help

Thanks in advance