Hvala.
What do you mean by "if the board has been modified ... " ? What board ? The morherboard ? I've seen it naked plenty of times so far and it doesn't look like it has been touched by anyone. No hw alterations as far as I can tell. How can one tell anyways ? Maybe I'm not looking at the right angle.
He's referring to your A500 motherboard being modified. I don't know the exact procedure, but it's well documented. What this modification does is to turn your 512K trapdoor "fast ram" into "chip ram" (also called graphics memory) which results in 1MB chip ram.
Basically, some games require 1MB chip ram, in which case 512K chip and 512K fast just wouldn't work. This is where the motherboard modification comes in.
It's possible that some of your games are not working because you do not have enough chip ram available.