As soon as i have selected my ship and load instant action, the game crashs.
I'm on Win 7 64bit, Q9550, Geforce GTX 260.
Can anyone confirm this?

Do you get any error message??
Try deleting this folder and see if it works - <install folder>\resource\images\planets
The folder is redundant and doesn't add anything to the game, however it can cause a crash on certain systems.

Happens to me too, regular campaign seems to work though.

EDIT: Removing the Planets folder did the opposite of helping, now the game doesn't launch at all, even putting the folder back didn't help.

If you haven't done so already, try installing it not in the %\Program Files\ folder and see if that works.

I have it installed in a separate partition in an folder that's accessible for all users on the machine.

According to the log it can't access the graphics card, which is weird as it worked up until I tried removing (and putting back) the images\planets folder. I didn't touch the flux.ini file, and looking through it, it looks like the correct values for resolution and that stuff are all still in there (it identifies Windows 7 x64 as Windows 2000, but that's probably to be expected from a game released even before XP):
[i]Operating system: Windows 2000Service Pack 1version 6.1 [Build #7601]
-------------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------
FLUX: [unknown] Approximate CPU frequency: 3013MHz
-------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------
LOADER: [unknown] Entering WinMain
FLUX: [unknown] Trying to create application of class "iwar2.icGame"
FLUX: [unknown] Application created successfully
FLUX: [unknown] Starting Flux services...
FLUX: [unknown] Starting resource manager...
FLUX: [unknown] Starting devices...
DXINPUT: [unknown] **** Initialising fcInputDeviceDI...
DXINPUT: [unknown] Creating DirectInput...
DXINPUT: [unknown] Looking for keyboard...
DXINPUT: [unknown] Looking for mouse...
DXINPUT: [unknown] Looking for joysticks...
DXINPUT: [unknown] Setting cooperative level
DXINPUT: [unknown] Initialising force-feedback support...
DXINPUT: [unknown] WARNING: Forcefeedback support unavailable
DXINPUT: [unknown] **** Device initialised OK
FLUX: [unknown] Starting input mapper...
FLUX: [unknown] Input mapper started successfully
FLUX: [unknown] Cannot create graphics device
DXINPUT: [unknown] **** Terminating fcInputDeviceDI...
DXINPUT: [unknown] **** Device terminated OK
FLUX: [unknown] Destroying application
FLUX: [unknown] Application destroyed
LOADER: [unknown] Leaving WinMain with return value 0[/i]