Of course decompressing failed: If you have a PART file remaining, it means the download failed at some point and you need to re-download the game. If it still keep happening maybe you should check your internet first.
I just re-downloaded it again, and all of the sudden it worked. I've already done this a couple of times so I don't know why it's working all of the sudden.
Again, I'm awful at computers so I didn't know anything about PART files.
