youtube messed up? does anyone else have the same problem??

[Phantom L]

my computer has been acting really werid latly and i`m trying to do everything i can to try to fix it. So recently i was away and turned my computer off for a week and when i came back everything was different. The History was erased and everything. The one thing that is really messed up is Youtube, it will work at first but then after i watch a couple of videos this comes up: "Hello, you either have JavaScript turned off or an old version of Macromedia's Flash Player. Get the latest Flash player." So what should i do? i tryed downloading Macromedias Flash Player but it wouldn`t download so i`m guessing that i have the lastet version? If anyone has any idea on what i should do PLEASE let me know!!!