Keyboard Windows 7 Doesn't Work

i am on windows 7 and for a week, my keyboard doesn't work. the key p, return, tab, and some others won't work. ma visual keyboard works fine - except the question mark - . i tried the pilots, and the computer says it has the best pilots so no need to update. i don't know where it comes from, but then, after a windows update, my keyboard came back to normal. it worked fine for three days and then, again, it screw up. it's always the same keys that don't work, so i don't think my keyboard is worn out. my computer is only one year old. it's a sony vaio laptop. each time i press the p key, for example, the start button -physical one- blinks. same for the other buttons. when i press the return key, the start button blinks. and while i am having this problem, my computer has trouble loading. sometimes it freezes and i have to unplug it and remove the battery to reboot.