It may involve some work, but the best approach here would be to strip down a capx as much as possible and post it. Otherwise, we're all just taking shots in the dark. Can't you obfuscate/distort/watermark your resources somehow so that they wouldn't be re-useable?
SgtConti's results are particularly bizarre...I wouldn't exactly call that a 'mid-range' system, unless we are throwing $5000 alienware's into the mix. No C2 game should be struggling on a computer like that.
Really feel for you on this, and I hope you can figure it out somehow...