string gadget containing the max transfer value. Change it to 0x0001FE00
It's just a spot where you can type in a value. It'll probably have 0xFFFFFFFF in it. That is a bad value. The A1200 HD controller has a nasty buffer bug that shows up on certain hard drives. The Max Transfer value needs to be something much smaller. There is some debate over what an optimal value is, but that 0x0001FE00 should work.
third reformat, that means that i have to put os back on,
You won't HAVE to. But, the problem is, while the max transfer was incorrectly set, every file larger than about 256kB or so written to that hard drive has a chance of being corrupt. Who knows how many problems are lurking undiscovered in a system like that.