Cannot boot from MOS 3.5

[simoninns]

If you try to load the game from MOS 3.5 the game crashes (with a corrupt screen image of the title) after the title page and music (before the actual game starts). Switching to MOS 3.2 (with the exact same Master 128 configuration) works perfectly.

[simoninns]

Another odd observation: When I plugged in a ROM cart (containing a BeebSCSI ROM in slot 1 and HiBASIC editor in slot 2) it then booted and ran ok from MOS 3.5.