There isn't a pattern showing and seem really erratic, isolated cases.
(personally, I find it extremely odd but, well, there has been a number of complaints now)
This thread is being opened so that, if you want to report which add-on tracks are not working (causing the game to crash, etc) we can all discuss it in here, test and look into it, etc, see if there are various users with same issue for a specific track, etc, mainly to see if there are patterns that may lead to a factual bug/issue, or not.
It's helpfull that, if and when your report an add-on track that isn't working, that you mention which track is it (and what version), what OS are you using (Windows XP, Windows 7, etc) and how is it crashing the game (if on game start, if with specific cars, on track loading, etc).
Edited by DucFreak, Nov 08 2012 - 12:40 AM.