Try commenting out all the code between OpenFile and CloseFile to see if it's this which is causing the hang. If so, you could add the file to an area rather than using OpenFile, to see if that helps.
I would like to know what BackgroundHALShouldPause does, and how to use it. While it's listed in the HAL Primitives report, it is not used in source code and it doesn't appear in the LMS HAL...
