The disk in drive A is not formatted???

When I try to run certain floppy disks, i get this error message:
The disk in drive A is not formatted.
Do you want to format it now?

I'm nearly postive that the disks are formated. One of them that does this is a Microsoft Return of Arcade Install Disk (worked when i installed it about 5 months ago), but it does the same thing with various other disks.

If you have any advice, please post it.
Thanks

could be that your Floppy drive's head is out of alignment(at about $10 to replace it's not worth paying to align it), you could have a flakey drive cable(but unlikely). I'd bet on a bad floppy drive, if there's nothing wrong with the floppy disks that you can't read.

I really don't know. Some disks will play and others won't. I'll try some that won't work in a different computer. If they work there, then I guess I'll have to replace the drive.
Thanks