Maybe none of those apps is guilty. However, I've seen some problems using FMRadio and not Petrovich (possibily not related to the program itself, I cannot say) and I'm just trying to guess which could be the problem so a Linux expert can tell me what Maemo configuration file could be affected. Indeed, I consider FMRadio a great and very important application to enhance the N900 experience and for sure it is a nightmare to get a stable product like with MMS (why Nokia has no Radio player installed by default?).
However, I have never used Petrovich for sending files through bluetooth (although I have it installed). On the contrary, I have had problems exiting FMRadio and disabling bluetooth (maybe not related to FMRadio but a buggy OS), and that's why I suspected FMRadio.