unexplained space consumption of a data drive on my Virtual machine

The data drive on my VM appears full but the actual space consumed is only 84GB OUT OF 200GB. Has anyone encountered something like this before? When I first saw this, the first thing i did was to check the size of the transaction logs to make sure that I don't have transaction log inflation. the log file size is fine.Does anyone have a clue or point me in the right direction to fix this? Please refer to the screenshots attached for clarification. Thanks![alt text][1] [1]: /storage/temp/3751-2space.jpg