It has been quite some time since I had a machine with a floppy drive, but if I recall correctly this was some function of the udev changes going on during the Slackware 12 development process.
It looks like this topic
talks about a similar issue, and a user proposes a possible fix in post #12.
Also, there were a few udev updates after the release of Slackware 12.2, and the changelog seems to indicate some issues were fixed. I don't know that it would necessarily help, but you should have all of the packages updated regardless. If you haven't installed them, the updates can be found on any of the Slackware mirrors