I really know for sure it wasn't accidently trigged (thus human error). As you can see I am not the only person affected with this bug. I was wondering what could cause this phenomenon. The only thing I have come up with, is that the mirc.ini file gets corrupted, for example by exiting mIRC while it refreshes the mirc.ini file.
This could cause the loss of the loaded Remote files and because it is impossible to have no remote files loaded it switches to a single aliases file and a single remote file.
But I am just guessing here. Still unable to reproduce.
The reason I reported the bug is that although I do not expect a solution right away, I do think it can be solved in the long run. I hope that combining my problem with others we get a better picture to be able to reproduce this in the future.