Ok, so removed the ASLA config and disconnected the USB Speaker. MAME4All starts working again and my roms spring back to life – as the other emulators seemed to work ok within the RetroPie environment I can only assume this is a “feature” of MAME4All. Hope this thread is useful is someone else is having similar issues – plus, if anyone has a resolution to this let me know!

Thanks everyone in this thread for the help and advice,