ok but neither my sprite nor icon banks are odd "lengths".
i just read elsewhere that the compiler forces banks to be even length (in bytes) which causes some bugs if you rely on the length of the bank being correct. But that is not the case here.
I read this thread which is exactly my problem, but i'm hardly going to redraw all my graphics!
i tried exporting the source as Ascii and reloading it, and reloading the banks, but that didn't help.
edit: also this: http://www.ultimateamiga.co.uk/index.php?topic=9308.0
so there's a good chance the compiler screws up if you include sprite or icon banks with the program... i might just save all the banks out and load them at runtime, might make it easier for people to mod it as well