I have attached a modified version of ChrisO's database.
Form 1, Setting the Default Property of field Text0 to ="""" & [A] & """" on the Property Sheet.
Access 2003: "ABC" (Incorrect)
Access 2010: #Name (Incorrect)
Form 2, using VBA to set the default of Text0
Me.Text0.DefaultValue = """" & A & """"
Access 2003: ABC (Correct)
Access 2010: ABC (Correct)