Good question. I had it running fine for quite a while. Burned through a few activations for no apparent reason, but still functioned. As of about 8-10 weeks ago, I'm getting the "Unable to run the application due to integrity fault message..." every time I start DCS in Steam.
I can keep opening DCS once I acknowledge Mig-21 error twice, so I can start and run other models, but no joy on the Mig. I've had them send me batch file to fix, but Gmail tags it as virus so won't go past server. (Not Leathernecks fault). The few other supposed fixes post online don't change anything. weird.
Absolutely awesome WHEN it worked. I assume this is temporary. I'll just hold off buying anymore from them till this glitch is fixed, then "I'm all in baby!" Don't have this problem with any other models.