So having replaced the Windows 7 shell with Attractmode everything seemed and Groovymame works on my Sega Astro CRT…however, if I try and run my Retroarch cores, which work fine when launching from explorer they display in a weird cropped way. Any reason booting directly to AM works with Groovymame and not Retroarch? Assume it is something to do with it loading Attractmode.exe and not explorer.exe? Looks like I’ll have to go back to Launchbox if I can’t get this sorted 
EDIT: Sorted via a batch script 
Need to create a batch script for launching attractmode, then create a shortcut, then put that shortcut in the startup folder - all good.