Pathname Trouble

[powsner@nlm.nih.gov (Seth M Powsner)]

    (resend of a message of 8/1/90, we're having Email trouble)
Having trouble accessing files on an ISO 9660 CD-Rom (on an Apple drive).
The CD mounts fine. No trouble evident in FINDER or using
   (choose-file-dialog)    which returns
     #P"UMLS_CD:DOC:CONTENTS.DOC;1"
when I select the file in question. However
   (probe-file (choose-file-dialog))   returns
     NIL
when I select the very same file.
   (probe-file (choose-file-dialog))   returns
     #P"develop, the disc:About this CD-ROM disc"
when I switch to an Apple CD-ROM and select on a file (and I can go ahead and
open the file for reading).

The problem also occurs when the file is copied to hard disk. I'm able to
get around it, for a small file, by copying it and renaming it without the
trailing  .;1    I guess there's some incompatibility in the pathname
representation or assumptions.

  Any ideas??
    powsner@qm.ycc.yale.edu