Need help in overcoming a problem in trying to shrink my OS (C) volume

[provlima]

I am trying to shrink my C partition to get more space on my Data partition.

My C partition is 191 GB and shows 65GB free and I assume 126GB of used space but when I total up the size of the files on the C drive (in the show hidden files mode) I only get a total of 99GB. The math doesn't add up.

Before trying to shrink C, I defragged the partition using W7. When I then attempted to shrink the C partition by querying the volume for available shrink space it showed that I could only shrink it by only 304 MB!

Is there a way I can overcome this problem? Perhaps by using another software program.

See screen shots below

 

[DavidE]

I use MiniTool bootable CD to resize partitions, then Windows isn't running, more space can be shrunk on . [URL="https://www.partitionwizard.com/partition-wizard-bootable-cd.html"]Bootable Partition Manager| MiniTool Partition Wizard Bootable Edition[/URL] I backup up everything to a different drive so i can restore/recover BEFORE making any changes. For the OS [C] drive i use Macrium Reflect free image backups. [URL="http://www.macrium.com/reflectfree.aspx"]Macrium Reflect Free[/URL] To get a better look at space used i have WizTree, WinDirStat, and TreeSizeFree - all free and portable. imho, WizTree is the best. [URL="http://antibody-software.com/web/software/software/wiztree-finds-the-files-and-folders-using-the-most-disk-space-on-your-hard-drive/"]Antibody Software - WizTree finds the files and folders using the most disk space on your hard drive[/URL] Before making any changes - BACKUP, BACKUP, BACKUP hth