Hi Richard, i just tried your OS4 WIP build, it "feels" faster while booting thus it completely locks up the system when going into the "emulated" workbench. I tried AIAB and AmiSYS2 (AmiSYS3 i cannot because of the damn - sorry - Winblows .exe format it's saved in). Booting from WB31 disk works, i think it may be the high resolution which causes the lockup, maybe some program, but i already commented out user-startup and WBStartup, so ... any hints? Ciao Hubert