OK, I've finally had the chance to tinker.
I ran: D:mame mame64.exe rygar -verbose from the command line in my cab PC
It started up Rygar fine.
When I left the game the screen filled with text, and as I grabbed my pen and paper to write down what it said, the text disappeared!
Does it save somewhere automatically? Should I press a certain button to freeze it?
I also did some more research online.
Other folks have had probs with the Mame /Attract mode combo, and saving hiscores.
Someone suggested that changing the workpath in the frontend menu to the mame folder had solved the problem for them.
I checked mine. Workpath was... blank. So - all excited - I typed in the address of the mame folder, saved it, and... nothing :-(
So to cheer myself up, I thought I'd have a go at Darius Gaiden for the 10p Arcade challenge.
I've been playing this totally vanilla - but as the rules allow for using and trimming autofire, I thought I'd give that a go. So I went back to the windows interface, accessed the mame .ini file, and changed the 0 beside 'autofire' and 'cheats' to 1. BUT NOTHING HAPPENED!
AAAARRRGGH.
This is really doing my nut in.
Think I might have to scrub everything and reinstal from the start.