Thanks to everyone for their input. This problem got solved by choosing REPAIR in Control Panel. I guess this explicitly re-registers some of Office's native COM components and does stuff that REINSTALL doesn't. I expect the latter just goes through a checklist and sometimes accepts what's there if it's already installed, maybe. I then had a separate issue with registering my own .NET dll for COM interop on the user's machine (despite this also working on other machines) though I think this was my error rather than Microsoft. Thanks again, I really appreciate it.

Excel VBA App stops spontaneously with message "Code execution has been halted"
In my bedroom the bottom half of all receptacles are controlled by one switch. Is it possible to have just one receptacle with top and bottom hot all the time?

The top half is hot all the time the bottom half is controlled by one switch.  Keep in mind there are six other receptacles in this room that are the same way controlled by the same switch. When I took the receptacle out the right side tab had been removed.  The top right screw had a black wire, the bottom right had a red wire, the top and bottom left screws had separate white wires.  I changed the receptacle out as suggested, I capped off the red wire and I capped off the white wire that was attached to the bottom left screw. I attached the other white wire to the top left screw and attached the black wire to the top right screw. I now have none of the receptacles working at all. What did I do wrong?
