however, when you click on it it does not

My xps studio laptop had no problem connecting to my router at home.  I recently bought a MiFi from t&T to bring down the shore and other get togethers.My daughter's dell Inspiron connects to it.  However my computer and my brother's dell netbook does not.  It shows the connection is available however, when you click on it it does not prompt for Wepkey and password on either one. I just returned from the shore and now my computer does not connect to my router. Keeps saying ethernet is unplugged.  I checked all the network adaptors and their drivers are up to date..