Hi.

First at all, thanks a lot for this software, really great.

I am making my first epub and all is going great.

But what I have noted it is that I can not open an epub, when I try to open an epub dont maked by sigil, the program crashes.

I work since Mac, Leopard.

I dont know if somebody have the same experience.

Thank in advance.
If the epub you're opening was made with calibre, that issue has been fixed and will be in the next release. The bug was not in Sigil however, but in zip modules Calibre uses. I implemented a workaround so it shouldn't be a problem any more.
Yes, it was with an epub made with Calibre. Thank you.
Another bug is that the program crashes very often just when is saving a document.
Witch OS are you using? I do not have any problems with the save function (using Sigil on Win and JJ)
Same bug I believe. Try building from source and see if it goes away.
Mac, Leopard.

Yes, using source goes better, but still crash sometimes.
Try to create a test case that replicates the problem and then create an issue for it.
Sorry, I dont understand or I dont know how to do it.
Well is it one or the other?

What I want you to do is create a minimal step-by-step procedure that when followed always causes a crash. Then create an issue on the tracker with this procedure and I will be able to find the cause of the crash and fix it.