Help with Panny 500u

I could use some information regarding my Panny 50" plasma. Last month I did a Firmware update to resolve a problem I was having with the TV not turning on unless I unplugged it then turned it on again. I do use a Cable Card and thought the update was the answer. It worked great for a month and now it is doing the same thing. I've got the cable company coming out tomorrow to check the card but any additional information would be appreciated. Does or did anyone else experience a remedy only to have a problem occur again later on? Thanks.