I have an 80 hr Series 2 model 240 with Lifetime Service. I am occasionally getting a message when I try to go into the Guide that I need to activate my Tivo. If I do a restart everything is fine for a few days and then I get the message again. Is this a sign that my hard drive is failing? If so, can I upgrade to a 160 hr drive without a problem. I was going to take advantage of the lifetime transfer that ended on Monday but I was out of town and forgot to do it before I left. Any help is greatly appreciated.