Hi Pepe;
Since you are coming from a very old PB version, here are some things to consider ...
1) PB 6 was ANSI and PB2017 is Unicode, so check areas in your App that might be ANSI sensitive. For example, calling external DLL's or MS-Windows SDK functions.
2) If your using the PFC. Make sure that you download the PB2017 PFC version and replace your old one.
3) Some firing order changes for Events were introduced a few times ... PB8.0, PB12.0, PB12.5 for example. Recheck your logic on Open and Constructor events - even on ancestors. These events may now be firing earlier in the Instantiation sequence where other resources are not ready. Remember that this happens faster too in an EXE vs running from the IDE.
A quick "litmus" test would be to run your EXE with the " /debug" option. This will slow down the App's execution and thus the event firing order / timing. If the App runs OK there (but slower of course) - then event firing order / timing could definitely be the issue.
HTH
Regards ... Chris