luckily i have all that is important saved on an external drive which i use for back up.

what i did is download a western digital diagnostic utility which i ran on my problematic drive. all tests it ran gave good results, no errors. then i ran one of it's functions to completely refresh the drive - making it all zeros - as if new and still unformatted. then i reinstalled windows fresh. now i've formated my problematic drive and so far everything looks like it's working ok.

thanks!