xcode 4.2: different compilation for debug and for distribution

Unfortunately i have a problem with distributing my a开发者_如何学Pythonpp. I have almost finished project, that is tested by me, and then I'd started beta-testing. Testers sent me reports about bugs, that I wasn't able to repeat. For example, app calculates finances of user (simple summing of data). And some times app adds some great numbers to result, that isn't right. I found that this bug appear only on distributed version. It mens that compiler differs for debug and distribution?

While debugging I tested my app on simulator and different devices, different iOS simply compiling project on target or making .ipa file form .app file.

Version for distribution I made with ad-Hoc provision, using build and archive on distribution configuration, and than using share for archive.

What's wrong? Why could appear any new bugs after distribution and how can I avoid it?