For one of my users, sometimes when she switches from Access to Excel and then back to Access a minute or two later, she gets a #DELETED error in the subform and one or more of the rows she entered has been deleted.
Is this like switching between two active windows? Because this is absolutely NOT normal Access behavior if that is what you meant. In fact, this cannot be a complete description of the problem because something else HAS to be going on here.
As long as any task window remains open, the local memory that holds a record of what Access did MUST remain intact. This memory retention is not an Access feature but a WINDOWS feature, that memory for threads will remain intact until the app exits and the window associated with the main process or task closes. Without it, no one could gainfully use WINDOWS at all because window-switching wouldn't work.
There ARE a couple of events you can use, called the Enter and Exit events, but they apply to the form. The overall app itself doesn't have separate events that I've ever seen because a quiescent app with no forms open has no code-usable context. To capture an event (at least to my understanding) you need a class module to be open and active. I would be willing to back down on that if other forum members have found exceptions, but I don't recall seeing anything like that.
If you had a setup with a "switchboard" form that never closes until you close the app, I would guess that you could use its Enter and Exit events for some things, but the truth is that if changes are being made to a form, it is the form's Enter and Exit events that would be most productive. THEY are closest to the problem and have access to all data on the form.
But let me ask this: Is it possibly the case that the database links to a spreadsheet and that your user simultaneously has the linked database and the spreadsheet open at the same time? In that case, I might expect destructive interference between the two windows. Otherwise, this makes no sense.
As to the name... beware of asking for what you want, you might get it. One of the super moderators can advise you on that one. I'm just a part-timer here.