Whenever I open CC, it quickly crashes with this error:

RTE Aborted! (x_x)

Abortion in file .\System\Reader.cpp, line 542 because:

Could not match property in Base.rte/Settings.ini at line 195!

The last frame has been dumped to 'abortscreen.bmp'

I have many mods installed, including Unitech and that massive base pack, and most of the dummy expansion mods I could find, although I'm not entirely sure this should effect anything. Can anybody help me?

My advice is uninstall (removing all the mods), re-install, test the base game to see if it works, and then install and test your mods one at a time. That's what I'm doing now in response to a similar problem (only I don't get any error messages, the game just crashes).

This occurs when the game decides that it is hungry and eats the lower portion of the settings file, just delete it and the game should remake a new one. You will have to re do and settings changes you made obviously.