Would that be 0x1ef0000?
I've always set it at 0x1ffff, myself. It's what the local Commodore shop suggested way back when my A1200 was new.
More recently, I've heard that 0x1fe00 may be an even more safe value, though.
If this is the problem, then you may officially hand me the "N00b of the the month" badge, and if I ever meet you in person, the beers / whatever are on me
:lol: The only reason I remember it so well is because I spent at least a couple weeks trying to figure it out before that local Commodore shop found the service bulletin detailing this little bundle of joy back when the A1200 was brand new on the market. :-P