Thank you for your reponse, Peter.
The links show up as odc extensions in the My Data Sources folder, don't
have a security database, just linking to an access database.  However.
It turns out that my users called up and sheepishly admitted that they had
copied the database to new location and were working from there; the links,
of course, were pointed to the old location.  Am somewhat embarrassed to
post this, except that it provides an answer for a problem.  The users did
not think to tell me of their actions, not realizing cause and effect, and I
did not think to ask them, since it is akin to reporting that the light does
not turn on after you have pulled the plug out of the wall.  Sothe moral for
me is, if users report a problem with mail merge, the first question is did
you move the database.
Claudette