Another observation:

While the N900 was connected to my laptop via USB in the Mass Storage mode, I made an internet connection before starting Saera, then initiated a "Search for food". The GPS icon flashed & established, but then the Modrana screen came up, crashed, & repeated until Saera was stopped.

The above loop happened when connected via USB in Mass Storage mode, but there was no problem when not connected via USB. This may have something to do with Modrana being set up to store tiles on the memory card on my phone.