Windows 7 Will Not Automatically Connect To "new" Wireless Network

I have a Dell laptop running Win 7 Professional. There are two wireless networks that I regularly use. One is at work (a large university with a huge wireless setup) and one at home. Both networks are set to automatically connect on my computer. If I only use one of these networks for a period of time, I have no access problems. If I log off or shut down the computer, or whatever, when I come back the computer immediately connects to the network.However, if I go from one network to the other, I have to enter the access key the first time I try to use the "new" network. I have to select the network from the list of available networks, and when I do, the "automatically connect" box is visible and checked, but it has not automatically connected. It is as though enterning the key for one network removes the key for the other.This happens on other wireless networks also, such as the one at my son's house, so it is not just the two networks I use most often. Also, my old Vista laptop had no problem recognizing and connecting to any of these networks automatically.