I've seen similar posts like this, but none dealing with exactly this problem. I have a fairly new Macbook Pro. It has a 500g HD, and it says I have 45.57g free. When I add up all the files, it comes to about 70g. Here is what I've done: emptied all caches from all browsers emptied the trash Ran DaisyDisk, but not sure exactly what I'm looking at. I even took it to the mac store and they didn't know what the problem was. The guy said he had never seen that before. He suggested I erase everything and reinstall OSX. Unfortunately I can't find the disks. What I'm working with: OSX 10.6.8 2gh intel core processor 4g 1333 Mhz DDR3 500g HD Please help. My Mac is running extremely slow and this is all I can figure would be the problem. Even if this isn't what's making it run slow, it's still an issue. Thanks!