Change your code from
If Me.txtPassword.Value = DLookup("strEmpPassword", "tblEmployees", "[lngEmpID]=" & Me.cboEmployee.Value) Then
lngMyEmpID = Me.cboEmployee.Value
TO
If Me.txtPassword.Value = DLookup("strEmpPassword", "tblEmployees", "[lngEmpID]= ' " & Me.cboEmployee.Value & " '...