Once I have more time I can do more test. Unfortunately, Scirra does not provide users with any tools to do any real debugging. Even *if* I determine it is just my computer, the *why* it is my computer is very important.
Well, the *why* is your computer, in case, it's your problem, not Scirra problem!
with all these problems, in your place, the first thing I would try to do would be a quick test of the project on another PC. Just to take the doubt off that it did not depend on me, or on my PC. Only then, eventually, I would open a thread to look for possible solutions..
Ashley spoke well, if you can not locate and isolate the problem, there is not much to do, and all this becomes just smoke and bad advertising for Scirra's tool.
So careful with this until you're not sure that not depend on you. So first of all I suggest you try C2 with your project on other PCs (maybe even on C3), and even more than one PC if possible, then if you find the same mistakes you can talk about it, but otherwise it does not make much sense to continue to discuss.