I seem to be strangely running out of hard drive space and started deleting things but still was running out of room. Then I ran a couple of programs (Disk Inventory X and OmnidiskSweeper) and they say I am only using 135 GB, but my 250 GB drive has only 20 GBs left. My math may be a little rusty, but that doesn't add up to me. I've run Disk Utility and it seems to be fine. Please help! Thanks.