The USB drive I'm using (Kingston DataTraveler 1GB) doesn't free up the space when I delete whatever files are on it. I've formatted it using both an Extended and FAT32 system. The actual files seemingly get deleted, but there will still be 300MB (for example) left out of 1GB. I'm finding myself always needing to re-format the thing in order to free up that space. Works fine on Windows, but not Macs. Am I doing something wrong? Not deleting it properly? A setting perhaps?