As FearaJinx says, try deleting your temporary internet files. I don't know what OS you're using but there is an issue with XP that stops anything but .BMP's being saved when the Temp files get too big. I've not experienced it with anything but IE, but that's not to say it's not related. Oh and also I'd do what sittingblue says 'cos it really does sound like your drives on it's last legs (half a year or not). Could be something mundane like a virus checker running in the background whilst you defrag though. It's always best to be on the safe side :)