One of my company's customers is experiencing a strange problem with an
Outlook add-in we built. The add-in is often disabled when some of the
users start Outlook, and they have to go into COM add-ins to add it
back. The problem is that this happens pretty regularly. They'd add the
add-in, it'd work for a while, but some days later, when they start
Outlook again, the add-in disappears again, and they have to add it
back again.

Some (but not all) of these users have
HKCU\Software\Microsoft\Office\Outlook\Addins\OurO utlookAddin.OutlookAddin
set to 0 or 1. But changing it to a 3 hasn't worked.

Are there any known causes that leads to an Outlook addin being
constantly disabled?

TIA