WITHOUT LNAV CAPABILITY DUE TO INOP DME; AN ACR CREW USES THE SYS IN ERROR.

Narrative

LEG WAS FLOWN FROM BOI TO LAS WITH THE FOLLOWING MEL ITEMS. AFT LAVATORY INOP; APU INOP; AND #2 DME RECEIVER INOP. AFTER DEP FROM BOI; LNAV WAS USED TO FLY ENRTE TO LAS. NORMAL NAVAID MONITORING WAS ACCOMPLISHED ENRTE BY BOTH PLTS AND NO OFF COURSE DEVS WERE NOTED. APCHING LAS WE DISCOVERED THAT LNAV WAS NOT TO BE USED WITH THE #2 DME RECEIVER INOP. WE DID NOT NOTICE THIS MEL RESTR PRIOR TO TKOF FROM BOI. A DIRECT CLRNC TO THE LAS VOR WAS THEN RECEIVED. LNAV PROCS WERE TERMINATED; AND NORMAL VECTORING FOR A VISUAL LNDG TO RWY 1R AT LAS WAS ACCOMPLISHED. I BELIEVE OUR FAILURE TO FULLY DIGEST ALL THE MEL IMPLICATIONS/RESTRS; AS WELL AS THE MULTIPLE MEL WRITE-UPS ON THIS ACFT (THIS WAS THE FIRST TIME I SAW MORE THAN 1 MEL ITEM ON AN AIRPLANE) CAUSED THIS OVERSIGHT. A MORE THOROUGH REVIEW AND DISCUSSION OF ALL MEL ITEMS PRIOR TO TKOF; BY BOTH PLTS; COULD HAVE PREVENTED THIS OVERSIGHT. SUPPLEMENTAL INFO FROM ACN 564310: ONE THING THAT MAY HELP IS ANY TIME THERE ARE MEL'S THAT AFFECT OTHER SYS; PUT IT ON THE FLT RELEASE IN ADDITION TO THE SUPPLEMENTAL SHEETS; IE; MEL 34-13 #2 DME (LNAV INOP) INSTEAD OF JUST MEL 34-13 #2 DME.