Actually failed RAM chips is relatively common. Others have rejected my theory, but I find this to be the most common on Apple-branded chips. Have a stack of bad boards with these chips to repair sometime. It's called bit-rot.
And there is no shut down command on 1.1. So be careful that you quit everything on the disk, given that it is stuck and you will not be able to eject before you turn it off, which could result in disk corruption.