Hi Mike,
What are they opening up in.  If  PDF files are opening up in
Internet Explorer,  I think it is because you installed plugins when you
installed the Acrobat reader.   Having browsers open up such files
within the browser is a big mistake, in my opinion,  and one that is
hard to eliminate.   Also don't install toolbars to open PDF files in
your browser.
   http://www.mvps.org/dmcritchie/excel/pdf.htm
   http://www.mozilla.org/support/firefox/faq#acrobat

Of course you did not say what really happens so that was my
guess.

A problem involving backing up files to a diskette or a CD-R  might
be involved with read only files even accessed in their own application
and even if restored to a hard drive from portable media.
   http://www.mvps.org/dmcritchie/excel/backup.htm#readonly

Direct use of newsgroups would be preferable to web based access.
Web based access that stores newsgroup postings as web pages
seriously impairs use search engines.   If you must use web access
then Google Groups at least keep postings out of where they don't belong.
  http://www.mvps.org/dmcritchie/excel/xlnews.htm#posting
---
HTH,
David McRitchie, Microsoft MVP - Excel    [site changed  Nov. 2001]
My Excel Pages:  http://www.mvps.org/dmcritchie/excel/excel.htm
Search Page:        http://www.mvps.org/dmcritchie/excel/search.htm