I had an issue with corrupt saves that stopped my Cities XL from working. Fortunately, I had little issue with parting with them because I did pretty bad. I thought I'd clarify for anyone who has this problem on how to fix it. Source: http://♥♥♥♥♥♥♥.com/ouf7ouz
So, long story short, it kept crashing after a period of time of being in-game no matter what save - new or old. I tried uninstalling and reinstalling the game twice, and a whole range of things that are irrelvent because they are wrong. Here's how to do it, with a little help from that link of course. The reason I am making this is to essentially show you a TL;DR version of it. So here goes:
Not fussed about losing all your saves? Go to "C:\Users\<username>\AppData\Local\Focus Home Interactive" and delete the file named "Cities XL 2012". This will fix it. Don't worry, it only removes your saves, nothing else.
Fussed about losing saves? Back them up and put the ones you want back in after starting the game up and starting a new map (after performing the deletion stated above, of course). Still doesn't work? You might have kept the corrupt save/saves. Try removing them. This can be hard for people like me who get too attached to these saves, but remember they're just files and if you did it once you can do it again or start afresh (better in my opinion, speaking from experience).
If it STILL persists to not work, first of all: I feel for you, truly, you shouldn't have to go through this, and second: corrupt saves aren't the problem. Which is good! Just uninstall and re-install and it should be fine and dandy AND you'll keep your saves. If THAT doesn't work, I'm not the guy to ask.
And now get onto the second reason for starting this discussion. Got a fix for that? Please, tell us in the replies for the sake of those affected. Has this helped you? Fantastic! I would seriously love to know, please. I like knowing I was useful, it gives me purpose :3. Has this/any resolutions from the replies not helped? DEFINITELY reply, it will save you. I urge you to do something rather than just giving up on the game as I did for months. Anyway, rambling over, enjoy your now-working game! You're welcome (hopefully) :D