This seems to be a prominent problem as of late. I don't have a firm idea of why it happens, but I believe it's related to a security update deployed by Microsoft some time a few weeks back, among other things. I have tried, but been unsuccessful at, finding a solution. It's related to Windows not letting you move the original handling.dat file to its storage folder to swap it with the Carmageddon version of handling.dat, thus enabling Carmageddon. I won't devote a whole lot of time researching exactly why it happens, and instead work on 3.0, which (as far as I can tell) doesn't suffer from the same problems as 2.x.
The incompatibility issues with retail EFLC and (possibly) retail GTAIV mentioned in the previous news post will still be an issue. This is because Rockstar has seemingly encrypted the handling.dat file in the retail version (but not in the Steam version). Why, I do not know. Whether it's consistent, I do not know. I only know that two guy shave reported the same issue to me, and as such there might be something related to the fact that the handling.dat file one of them sent me was filled with garbage. The regular handling.dat file is plain text.
