Why would a computer be losing space in the hard drive?

If you are losing disk space constantly for no good reason, then you have a old type virus that a simple anti-virus scan will detect and remove Music and Video can chew up memory like nobody's business. Those files should be sorted through and non-used files deleted. The next big culprit is how your computer is saving files. If you haven't run a disk defragmenter before, now is the time. On a Window's based operating system, select Start Menu > Search > Files and Folders > type in "defrag". Then, when you see "Disk Defrafmenter" appear in the search terms, select it. Click on the "Analyze Disk" feature and in a minute you'll have a picture of how messy your disk drive is. Likely, your computer will reccommend that you proceed with the Defragmentation and you should start this process. The whole process should take 30-90 minutes. Upon completion, you should see a vast improvement in performance!