Well for what its worth the solution, in my case, was to rebuild the combo boxes and then add .value to the SQL
Why this was needed I do not know but anyway the new code is
varProj = DLookup("[lngPr]", "tblProjects", "[lngPrEntity] = " & Me!txtEn.Value & " And [lngPrType] =" & Me.cboProj.Value...