Hi All- I'm running XP Home SP2 on a Pentium D 3.0 with 2 GB Ram. I have a 120 GB and a 250 GB Hard drive. The 120 is partitioned into C and G Drives. I just did a clean install of XP onto the C Drive, which is where my operating system has always resided. The problem is: An 'Unknown' file/folder is using up 35.1 GB on my C drive. Nothing near this large is visible in Explorer, even when I checked 'Show hidden files'. I've used WinDirStat, and it shows an 'Unknown' something using up the space, but cannot identify it or delete it. I've used the Clean Drive utility. I've run SpyBot and AdAware, as well as done AVG virus scans in Safe Mode. I even defragmented and scanned for disk errors. My Page File is not on the C Drive. I have no idea what it could be. Here's my HJT log: I'm not sure if anything related to my problem would show up on this HJT file. Any help is greatly appreciated! Many Thanks, John PS: I also posted this in the Windows OS forum, as I'm not sure if this is an OS or a malware problem.