However I am getting the following message: Disk I/O Error Replace disk...
The a: drive does work because I can view the contents of the diskette from 'my computer'.
I have tried changing the drive with one that I know works, but I get the same message. I have also checked that the drivers are all up to date and they are fine too.
This is happening on a Dell Dimension 4300 running XP Pro. I have an identical machine which works fine.