Downloaded the beta 27 upgrade.
Ran it, rebooted, 27 was fine last night.
Went to start beta this morning, got init failure.
Renamed exe file to aceshigh2.exe.
Renamed settings folder to oldsettings.
Reran the beta27 upgrade.
Rebooted, 27 works.
Saved the new video8.cfg, put it in my old settings folder which I then renamed back to settings.
Hey presto I'm back in again with full settings. Beta 27 still working.
Not sure what's changed but it beats uninstalling & reinstalling from scratch.