For some reason my hard drive almost reached it capacity of 140 GB when in fact there is no more than 60 GB on it. I tried to erase and defragmenting and nothing works. I am assuming that it happened due to shortage of memory, so now the OS is using the hard drive's memory. Is there a way to have those lost GBs back? I think it is a problem with shadow files, but I haven't found instruction on how to erase them.