My exact fix:
Delete the game from my system.
Download it fresh.
Double click on the downloaded file, Planeshift.dmg (or something close to this).
Drag the Planeshift app (that appears when opening the downloaded file from previous step) to my Applications folder.
Wait for it to transfer.
Then delete the Planeshift.dmg file (I have to unmount it then delete, but however you get rid of a file on windows 7, do it).
Now I have a Planeshift folder in my Applications folder. Go into the Planeshift folder and double click on the psclient (not pslaunch, don't mess with any settings, just open up the game).
This worked for me.
What didn't work for me is opening the game when the Planeshift.dmg file was still there.
Does it help?
Edit: Try using direct download and not torrent. This should not matter I think, but it is what I did.