Hi, Rich. I'm familiar with this waring too. I get it when there are two forms open which draw their data from the same table. It seems that the first Form thinks IT has the exclusive task of altering its bound table's data and detects that something other than itself has made a change. I've not been able to resolve this. Where possible, I find a workaround.

I'm trying to resolve the same issue in my database. The problem seems related to a second form editing a field using a ComboBox followed by an SQL or Recordset write of the selection to the first form's bound record source table. However, it doesn't seem to be happening when my 2nd form changes values in TextBoxes bound to that same table. There, my changes from Form 2 are immediately reflected on Form 1 without a requery or any further action. Maybe edits using Combo's should happen on Form 1 - the original form (unhide a control?) and reserve the 2nd Form for TextBox editing only.
This happens when Form 1 is bound to a query generated from a table full of foreign keys, with strings from related tables replacing the meaningless foreign key number content. Would a 2nd form be needed at all in that case? (thinking out loud)

Hi Richard, that "another user" is you.  You made two changes to the same record at the same time and Access can't decide which change to accept.  This is not just a warning, but a problem you need to fix, otherwise you may lose data.  Find out which two changes are being made, and move one of them to a different time (usually via a different event).