[Guest]

Is everything else that you have installed in the c drive more important than il-2? I mean, if you have (say) BoB2 installed: try copying that to another location to give you more space for il-2. I'm not saying that il-2 is more important than that; but this could be an alternative. At least seeing if it works well in the c drive could at least give you the answer that it will run (but only in this location)