Computer nerds experts,

Do you have any suggestions on how I can clean up my computer's hard drive. I have a 101gb hard drive on a ~8-9 y.o. computer that runs Windows Vista & have recently been alerted that it's nearly filled. I've run a disk cleanup (twice) & deleted some random files, but right now it has about 3gb left (after I had it up to 5gb of free space, it went back down to 3).

A few days ago I did a Malwarebytes fullscan & it found nothing. Before that I used CCleaner, so it doesn't make sense that all that hard drive is being used.

Thanks in advance.