Hey, thanks WyomingKnott. I've downloaded the WinDirStat and it solve my problem. I saw all the hidden junk files and read only files that windows created in this software. But the big culprit is the Recycle Bin, for some reason it didn't actually emptied the recycle bin when I execute the "empty recycle bin". No files are displayed in the recycle bin after I executed the command giving me the impression that all files in the bin were totally deleted. But when I executed WinDirStat it still reporting that over 2000 files are in the recycle bin (which are files I previously deleted)...I went back to the recycle bin to check, but nothing displayed in there. So I deleted the files again in the WinDirStat and all the junk hidden and read only txt files that the microsoft net framework created in the Windows Temp dir., which I also thought were deleted when I did the built-in clean-up utilities in Windows. All in all I've freed up 25GB. THis software utilities is GREAT!!! You really need specialized software to clean things up and not rely on the built-in utilities in Windows...they don't work sometime. Many thanks again for the help!