I had a problem when disk space was disappearing for one server. I had deleted and stopped all logs and but the disk space still was getting less each day.
Usually I used WinDirStat tool to find what is filling the disk. This time it didn't help. Also tried running it as administrator, but still no luck.
I googled around and found tool called SpaceSniffer, which helped me to find necessary information. This time "System Volume Information" had eaten all the space. I resolved this by enablig/disabling shadow copies on the problematic volume.