internet connection lost on reboot

I have: New XPS 420, 4GB, 500GB hard disk, GeForce 8800 GT, Vista Ultimate, Core 2 Quad 2.4Ghz, etc., DSL cable modem

I tried setting up a home network with another computer, but seem to have created a new problem.  I lose my internet connection when I reboot.  Then I have to go through this process: Network Center says "There is more than one active network connection on this computer. Unplug or disable one of them." 

I have only one physical plug to the cable modem and no wireless connection. I manually disable one of the two displayed networks, then use repair, then the internet connection works again.  Seems like everything is fine until I reboot and then I have two networks again. One is the one I named (Network A) and the other is Unidentifid Network.  This is like Ground Hog Day!  I don't know how to make the changes stick.

My other computer is wireless connected and is working fine. Probably because it is running XP!

UPDATE 4/27/08: After one hour getting remote assistance from Dell Support, which was very competent, we agreed that my Vista was corrupted and used the recovery partition to reset to factory settings.  Now everything is fine, but of course I wasted a whole weekend on this problem and all the reinstall business.  Not a good start for the first week of my new computer!