On Win95c copying files to a fresh floppy disk, first time is fine. However subsequent attempts using the same disk result in 'not formatted' messages, or 'cannot read from device' messages.
From that point forward, the floppy disk is useless.
Once this stage has been reached, trying to read the disk in other computers yields the same results.
Given that I need about 500kb of files off it, this is somewhat annoying..
The drive has been replaced with a new one - no change - and it has no modem, so viruses are unlikely.
I tried to virus scan a disk using Housecall, but it came out clean (though I wonder whether in fact it was read at all).