I have a windows 2008 server and I ran into a situation, where one of my disks was showing up incorrect used space information and that was driving me crazy!
As you can see below, my drive was showing up as 81.6 GB utilized but in reality, I was only using 8GB of it. So where was the extra space coming from?!
I checked my shadow copy settings because sometimes that is the culprit, but I had none configured.
Also, I ran tools like SpaceMonger which I use to identify space issues and that did not give me anything. So after a while, one of my team member pointed me to check the hidden files and system files and then I checked the size of my hidden "Recycle bin" which I found to be eating up all that extra space!