Rob,
Thank you for responding.
This is a known and quite a common problem for those upgrading from 1.5 to 1.6, or those installing 1.6.x under some conditions. Check out http://bugzilla.wikimedia.org/show_bug.cgi?id=1322, for instance; and possible fixes/workarounds/etc.
While the issue is known, the workarounds are a little above my head. People suggest, for example, to use a shorter key length ((`cl_sortkey`(78)), but I have no idea where to implement that.
Another person says "Changed table definition in CVS HEAD for 1.5; cl_sortkey is now limited to 86 characters". Again, I have no idea how to make this change.
Is there a slightly more verbose description available about how to do these things?
-- Dave M G