this is what i think:
you can't enter either csppc or p-iv early startup because you are using a keyboard adapter with a ps/2 keyboard and not an original amiga keyboard (or?).
csppc is set to default 31khz out on the the rgb port of your amiga, caasing problems when p-iv is scan doubling to your lcd monitor. you have to set csppc not to default 31khz. hold down the esc-key (may not work because of the above).