I have a Gateway PC with an Athlon triple core processor, 3 gigabytes of RAM, 2 300-gigabye hard drives, and Windows Vista Home Premium operating system. I've run into a problem with my C drive filling up. When I check drive properties in Windows Explorer I find that there are 5 gigabytes of free space on my 287 gigabyte hard drive. However, all of the folders and files only total about 100 gigabytes. I've taken folders off the C drive to free up space but the new free space eventually fills up. I've run TrendMicro antivirus and Norton 360 antivirus, both of which found no viruses. I've run WebRoots SpySweeper and found two spyware files that were quarantined; this didn't fix the problem. I've run ChDsk and found no problems. My PC isn't backing up to the C drive so this shouldn't be a problem. Has anyone else encounted this problem? Is there a way to see what is filling my hard drive. I know this sounds like a virus but I can't find anything.