|Yeah, it might be failing or slightly misaligned such that it reads some but not all disks. Or the disk may be flakey and not work in every drive.|
Is the drive it worked in a 1.44 or 720?
Was the disk originally a 1.44 and then reformatted to 720? Was it formatted as 720 in a 1.44 drive?
Do you have any other 720 bootable disks you can try or can you make some on another machine?
When governments outlaw guns only outlaw governments will have guns