If the mod does not work for you, please look here first:
http://wiki.jc-mp.com/Troubleshooting

Here is a list of common issues with solution described on the wiki page:
- Renderer Failed to initialize: Failed to create effect
- Fatal exception occurred when launching JC2MP: Waiting for remote thread failed
- Failed to create Just Cause 2 process: The requested operation requires elevation.
- Game crash on startup.
- Black or white screen.

If you can play the mod, but it crashes often:
- Try disabling Steam overlay from the Steam library.
- Disable all overlay software like Fraps, Xfire or Raptr.

Please create a new discussion if you haven't found a working solution.