This is unbelievable.
I was working on a small platformer since last week, and it was starting to get really good, I think it was going to be my best game ever.
MMF2 thought "Let's fuck him" and suddenly some "bad object" shortcut showed up from nowhere in the events menu, and everything messed up, the actions were gone and some events too, so I had to work on the event list editor. Then I quit and when I restart MMF2, it says the only level I did (the template) was corrupted and it was going to be deleted.
Try breaking the habit of testing the game by pressing F8. Everytime you test the game, make a build of it, and save it. When you're up on 1000+ events (my project Parilis has a server with 400+ events, and the client has 500+ events and it crashes a freakin' lot!), you might want to consider this technique, testing the game with the exe you built.
I would also recommend getting the latest build, but I think you know that.
I've had my first Bad Object error in 244. Really messed up my engine. Everytime I make a big change, or am about to copy over my 'global' events subfolder (thanks MMF2 for multi-level events folders) I make a new save for the game. For Tormishire I'm up to Tormishire32.mfa. It absolutely eats HDD space though. More so when you have auto-backups too.
Even with backups Bad Objects totally mess up work. Shame they're still present in MMF2 really.
"If this ever happen again, I swear I'll sue Clickteam"
Now now, don't be silly. You should perhaps take the time to read any disclaimers with Clickteams products - especially sections along the lines of "Clickteam will not be held accountable for any damage done to your computer or the software contained within".
Everyone has these problems, yes they can be annoying, but they serve as a helpful warning to frequently BACK UP YOUR WORK!