Unable To Change WEP Passphrase

I have just purchased a new HP laptop with wireless network card; after much fussing I was able to connect to internet successfully but only WITHOUT any protection on the router. When I attempt to apply WEP it doen't get a signal back from router. During process of trying solutions, I changed the passphrase on the router to a 5-character word (it was an 8-character word which has been working for more than a year with other wireless laptop) but new laptop with Vista Home Premium wants 5 or 13 characters, so I changed in the router. BUT the Properties of the linksys connection still shows the old (8 character) password and even when I change it and save out, it goes back to the old one. I have tried to get at those properties several ways but no luck. Note: I can get connected through this router if I hardwire the laptop AND am successful wirelessly as long as connection isn't protected (obviously not good idea.)