I just got off the phone with Adobe support. The problem seems to be with a file in the SING folder (Library > Application Support > Adobe > SING. When this folder was moved to the Desktop and InDesign restarted, the program operated properly.
Then InDesign was shut down. The SING folder was moved back into the Adobe folder and opened. Inside the SING folder are a pair of nested folders: Mark II > Datastore. The file SINGmeta.dat was trashed and the program restarted and worked properly. (Although for some reason a Sample Button library window was open?!)
The only difference between my earlier use of InDesign and current use was a transfer of the contents of a Mac G5 to a new Quad-Core Intel Xeon machine.
having spent several hours troubleshooting this, I hope this helps someone.
Don O'Shea