When I start GTA IV everything works properly but when I activate LCPDFR my game crashes and displays the message "Fatal Error RC20: Please reinstall game."  This never happened before, and I already removed all mods and reinstalled the game twice already and still the same thing happens when LCPDFR is activated.  I have a top of the line computer so that's not the issue.  I hope someone can help.

Did you uninstall any previous versions of LCPD:FR BEFORE you installed the new one?

Yes

Did you uninstall any previous versions of LCPD:FR BEFORE you installed the new one?

​Yes I did uninstall lcpdfr.  I am using version 1.1 .

RC20 errors are caused (mostly) by car mods. When you uninstalled the game, you deleted your Grand Theft Auto folder too, correct?

Yes, I did.  I will get rid of the car mods again then try, but it only happens when lcpdfr is activated.

I restored all vehicles to default and now it works!  Thanks for the help!