(Found my password Scarn)
I had the same problem, but only on my laptop. Had to enter planeshift from the setup screen or it would crash. I added the - to the desktop shortcut, (rightclick the program file and send to desktop, rightclick the shortcut and go into properties, don't forget to apply the changes) and magically I can use it without setup.
In case it can help:
Laptop; Compaq 2525us
Windows XP home service pack 3
Pentium 4 2.4 non hyperthreading
1 gb DDR
ATI 320/345m with a modded driver (the latest authorized driver will not run Planeshift at all)
Desktop; custom built and upgraded last about 2 years ago.
Windows XP home service pack 3
Pentium 4 2.8 HT
2 gb DDR2
ATI 2600 overclocked nearly 20%