ezurlalias screw up

I couldn't update the site for the past few weeks: every time I tried to edit something, I'd just end up with the frontpage (viewing pages worked fine, though). I suspected it was ezurlalias' fault and after a lot of fiddling I was proven right: there was a wildcard URL alias (weirdly enough, using is_wildcard=2 whereas I suspect 1 being the normal way of doing it) for the root node. Which obviously caught everything but the urls that actually exist. Now I'd really like to know how that got there...