A suggestion:
The quality of floppy disks is pretty poor these days. You can get poorly formatted disks from any manufacturer.
The safe way is to reformat your disks on your PC before you use them, even if they are brand new. Don't do a quick format but a full format. The format program will tell you if there are any bad spots on the disk when you are through. IF THERE ARE, Throw that one away.
Do this also if you are using a disk that you used before -- they don't last very long anymore. A floppy can be very unreliable.
Taking the time to do this will avoid many problems.
Walt