This is the JP1 beginners forum. There's no such thing as a stupid question in here, so post away, but this forum is just for JP1 users and people considering JP1, non-JP1 users please use the appropriate forum above!
I think the problem was that I'd loaded RM into Program Files - I think somewhere I'd come across some recommendation to put it there, but it seems that's now a bad idea as that's a semi-protected folder. Reinstalling it in a Desktop\JP1 folder seemed to do the trick.
I've got my issues all largely sorted out now, thanks. I do have a couple minor remaining questions on the Pioneer TV upgrade; I've started a new thread for that.