The range points to one cell. If it helps, the error previously
occurred when trying to populate Combobox1 with a named range which
was on another sheet, but it threw out a 1004:runtime error method
'range' of object'_Global failed so I changed the code to

ComboBox1.AddItem "A&D" 'ListIndex = 0
ComboBox1.AddItem "A&D MANAGER" 'ListIndex = 1
ComboBox1.AddItem "DEPARTMENT MANAGER" 'ListIndex = 2
ComboBox1.AddItem "PROGRAMME" 'ListIndex = 3
ComboBox1.AddItem "PROGRAMME MANAGER" 'ListIndex = 4
ComboBox1.AddItem "SERVICE" 'ListIndex = 5
ComboBox1.AddItem "SERVICE MANAGER" 'ListIndex = 6
ComboBox1.AddItem "TECHNICAL" 'ListIndex = 7
ComboBox1.AddItem "TECHNICAL MANAGER" 'ListIndex = 8


and it then failed on the next attempt to use a named range....
TextBox8.Value = Sheets("User ID Control List").Range("userid").Value


It makes me think that perhaps it is something to do with access to
these ranges but other than that I'm stumped. The fact that it only
affects some users and not all throws me too.