@gianko - the contacts that caused the crash - apparently there is a bug in the address book that makes some contacts corrupted and while working fine for some apps, it crash others. If you will try yappari (whatsapp for N900) it will crash as well, what was suggested there is to export the contacts, remove them from the phone and then import them back. I don't recommand doing it as you might lose your contacts if you done something wrong.