I take it that you have a home page that needs a connection and so the browser calls up the DUN first.
When I did use DUN I never did it that way radean. I put a shortcut to the DUN on my desktop, selected the "Never dial a connection" option in Internet Options, and then opened up the shortcut window and dialed out before opening my browser. I could then check that the DUN number about to be dialed was my own ISP number, and not a rogue dialer that may have slipped in.
Would that work for you?
Also, I made my own home page and keep it on my computer, (it's not publised anywhere), so that whenever I start the browser, it doesn't immediately look for a web page.
When I start the browser, the DUN window, box, whatever, starts first, and is then "behind" the Firefox start screen.
As said, a minor issue, but being a doddering old fool, sometimes I find myself waiting for the DUN window to pop up so I can dial out. Even though I know (well, I realize now), that it is already open, just not seen. Yes, it is on the Taskbar..
Any help here for forgetful people would be appreciated.
Oops, sorry, Running XP Home, and FF browser is NOT set as default, but the opening shortcut is set as normal window, to open.