My guess is that you need to clean the heads on the PSR 2100's floppy disk drive. Yamaha recommends cleaning the Floppy Drive after every 10 hours of use. They also recommend a "Dry" method cleaning disk. Since Radio Shack is no longer doing business in England I'm not sure where you could pick up a cleaning disk kit for the PSR's Floppy Disk Drive but there must be someplace. The one I use is from Radio Shack and it includes a cleaning 'solution', ie., "drops" that are placed onto the cleaning disk. NOTE: If you get a kit with "drops" use only one or two drops at the most on the disk. Simply insert the disk into the Floppy Disk Drive (while powered ON) and you will hear the disk begin to 'churn'. It will churn for roughly 30 seconds and when it stops churning it is done and your Floppy Drive's head is now clean.

Hopefully that will clear up any 'errors' you've been getting of late when using your PSR's Floppy Disk Drive.

If that doesn't cut the mustard you may have a faulty Disk Drive. It would be under warranty though. If worse comes to worse you could even replace the faulty drive (speaking theoretically here) with a common Floppy Drive bought at a computer store, etc. Replacing the Drive is not that hard to do if you know what your doing.

Best regards,
Mike