I have had this working previously, although i think it was a 4.X version of cisco. It was around June.
I can see that it is contacting the gateekeeper, yet I do not get asked for my username and password.
I have recently had a new laptop from work which cam with 5.0.04.430.
I have used a few different pcf files and they all result in the same issue, not getting the username and password box.
At work I have patched a broadband connection to my desk, not sure who it is, its on my list to find out, but it works Ok on that one, which to me points to either my broadband or my router.
I have changed the DHCP lease period form 0(which it has been for a few years) to 5 days, and that hasn't made a difference.