Don't allow changes to code while application is active
It has been known for years that Access applications can become corrupted if you update code while the application is active. I've been a developer for many years, and I still find myself editing code at times with an active form in the background.
Given the very serious risk, there is no reason why Access should permit users to edit code while the application is active. Therefore I recommend that code be automatically locked while the application is active.
I realize that VBA is a separate product, but there must be a way to do this.
Ben Sacheri commented
Microsoft, if you decide to add this, make it an option in Access or VBE. I've been burned by this but I also really like being able to step through running code and making changes to it.