I have an Esquire 4GB USB, I've been using it for the past 2 years or so, transferring files and other information from one pc to my pc and vice versa. The problem I have now is that it has free space of 1.77 GB and used space of 2.21 GB, but everything in the USB amounts to 202 MB. I don't get it, how is it possible for the USB to have a used up space of 2.21 GB? I think that maybe it's because the files I have put in the USB which later I deleted must be still in the USB somehow. My computer shows hidden files so that's not the case. If somehow files are still in there, how can I get rid of them? What software must I use?