on this cases when you load the wrong project,you have to wait until it loads(can take a while on heavy projects)
then close it and open the right one.
i cant see (or dont know) how to close/stop project while loading !
CTRL-ALT-DELETE would be my only suggestion.
mmm… i can pull out the PC power cord as well 
seriously should be some way to do that, on the first sec when loading there is an “Abort” tab on loading window and then it disappears , maybe its a bug ?
Is there a way to abort project load?
Large projects take time to load, and sometimes I open the wrong version and realise only after I’ve committed to loading it.