How did 3 GB of disk space get used up by itself?

Yesterday, I literally watched my free disk space number go from 14.1 GB to 14.9 GB to a different number. Now, it's at 11.9 GB. I haven't downloaded or installed anything. What's going on? I have changed my paging file size. Does that have anything to do with it?How did 3 GB of disk space get used up by itself?
run ccleaner man. that thing will clean it right upHow did 3 GB of disk space get used up by itself?
If you increased the page file size that would account for some of the decrease.

Windows creates a lot of documentation and temporary files also.

If you don't have a limit set on Internet Explorer temporary files, they can use a lot of space too.

Try running the built in disk cleanup tool. It will show you how much space is tied up in such things.