Steam eating up HDD space?

So my drive for games is getting low. I was installing Wolfenstein, a hulking 44GB. It was just starting by allocating disk space. I had to cancel it because it was freezing dota. Now 10GB has disappeared and there is no sign of any piece of Wolfenstein.

Odd. Pre loading Shadow of Mordor while playing Dota 2 and no problems...

Steam steals the disk space for a download ahead of time so it won't fail later on due to being filled up by something else. Try a program like WinDirStat, makes it super easy to see what's eating up space.

Yep. If you've also had other downloads that you stopped or paused those are also allocating disk space as well. You can usually figure out what you have by going to

Local Disk Drive > program files (x86) > steam > steamapps > downloading

You can usually tell by the size of the file which corresponds to which game. I also wonder if the freezing of dota might be caused by the virtual memory being used from the hard drive and it ultimately running out of space from the Wolfenstein install? Either way it might be a good idea to start thinking of installing another harddrive or deleting / moving a few things off your main drive.