My C drive is supposed to have 50GB capacity but quite often it flashes up as only having as little as 34MB space left. I go through the routine of running disk cleanup and getting rid of temporary files etc which gets rid of only a few MB of stuff. I've downloaded a scanner to see what uses the space, but I don't really want to delete things that I don't understand. Next time I check the amount of disk space available it has suddenly, and for no apparent reason, jumped to 2.5GB. Can anyone explain this? Is it restore points? Is it to do with sleep-mode? Can I do anything else to free up any space?