Audrey, I still use the PSR9000. There are a couple of things to note:

The 9000 has a limit on FILES in each directory -- 250 tops. Thus if your folder on the floppy disk has more, break into more folders and use as multiple folders/directories. I use 200 or so as a max in each directory.
Ditto when transferring to the internal hard drive (if used).

When you load the floppy disk -- press the Disk Direct button on left side to have the files read into main screen properly. If in multiple folders, after loading use the up and down arrows below main screen to get in and out of directories.
More basic: floppy disks can be tricky when different machines format/read them. Try formatting a clean 1.44 floppy (HD) on the 9000. Then use in the PC. If it cannot read it/copy to it -- one of theses floppy drives is misaligned, dirty, etc.