The expression On Click you entered ...
I was getting the below error message in Access 2003 when I clicked on a command button. Likely because I was working on a form module and possibly saved it while the form was in regular view and not in design view.
"The expression On Click you entered as the event property setting produced the following error:
Object or class does not support the set of events."
Commenting all the code behind the form did not fix the problem.
Setting the Has Module to No and saving the form, surprisingly, did not fix this problem.
Decompiling the MDB also did not fix the problem.
This problem also existed when I opened up the MDB in Access 2000 and clicked on a button on the form.
Importing all the objects into a new MDB finally did the job.
Hint: when importing lots of objects into a new MDB minimize the database container window before importing. Access will import much, much faster.
As a bonus a child sub form which wasn't saving the parent value in the child table also started working properly.
As a side note every hour or two I always go into Windows Explorer, click on the MDB and do a Ctrl+C and a Ctrl+V to copy the FE MDB. Every few days I zip all those and move them to an archive folder.