I have a mystery which I cannot solve. I've installed GTA IV and got the RNM 40 error. I followed the advice posted here by going to compatabiliy and setting the game to run in Windows 2000. It did not fix anything. I even shut down my firewall thinking that it could be blocking the game from launching. Didn't help. Today I've set yet for another quest to try to find a solution to my problem. When I launched the game I got this message "The application has encountered a fatal error and must close." and then it said to restart the game or contact support. So I did just that, although I haven't heard from GTA support yet. I've installed service pack 1 for Vista and that didn't help either. Then, I've downloaded one of those programs tha helps rid the computer of any corrupted files. When I tried installing the program an error message pop up saying that the program does not support 64 bit Vista??? I don't know what else to do but I'll keep looking, maybe there's a problem with my computer, and not the game. Anyway, I'm wondering you can give me any advice on how to solve this dilema.