Hello Mr Whippy,
does the OF start when you connect your clip to the computer? I am not sure, but when your clip is powered off, you connect it to the computer, the USB mode of rockbox should start and not the OF, so after unplugging it there should be no database refresh from the OF. But anyway, to avoid that refresh, safely remove the clip from the computer, switch it off first and then unplug it. If you power it on then, rockbox should start and there should be no database refresh from the OF.
Hope that helps.
Greetings
c_k