[Zubersoft]

There aren't any log files at the moment. I can certainly put together a build for you with logging in it. Or I may just start implementing a logging framework so that I can start capturing data for solving bugs if the user turns logging on. 

When switching between songs, the previously loaded PDFs have to be cleared out of memory. Perhaps this problem can occur under certain conditions when the PDFs are cleared. If that was the case, changing the setting for Settings->Display Settings->Render Preference should have some impact on that. You could try switching that setting to see if it helps with the issue. I'll keep an eye out for what you have described as well. I'm rarely able to use the app for extended periods of time like what you are describing though as I spend most of the time either modifying code, tracking down and fixing bugs (which involves restarting the software over and over) or supporting customers. So adding logging probably is the best way to gather the information required to solve this. 

Thanks,
Mike