POTENTIAL CONFLICT ENSUES WHEN MULTIPLE ACFT EQUIP PROBLEMS SURFACE DURING AN ILS APCH PROC.

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UPON BEING CLRED FOR THE APCH THE ACFT WAS CONFIGURED FOR A COUPLED APCH. FO ILS TUNED AND IDENTED ON 111.7. MINE ON 112.0 (MONITOR VOR) FOR DME. THE AUTOPLT FAILED TO CAPTURE THE ILS AS WE ENDED UP S FOR THE APCH. WE CORRECTED BACK TO THE R AND ATC KEPT US AT 5000 FT BECAUSE OF 28L TFC. AFTER GOING BACK TO THE N TO REINTERCEPT ILS 28R I SWITCHED TO 111.7 AND WE BOTH HAD A GOOD CENTER INDICATION. ON THE DSCNT; THE AUTOPLT/AUTO THROTTLE DISCONNECTED ITSELF AND WE FLEW RAW DATA ON THE APCH. BOTH NEEDLES WERE OFF TO THE L AGAIN TELLING US WE NEEDED TO CORRECT AGAIN; GS INFO WAS GOOD. AS WE APCHED THE ARPT THE NEEDLES ON BOTH HSI'S WENT L TO R TO L VERY QUICKLY. FOLLOWING THE NEEDLES; WE FOUND OURSELVES S OF COURSE AGAIN WHERE ATC HAD US EXECUTE A MISSED APCH AS WE GOT CLOSE; BUT STILL HAD LEGAL SEPARATION ON 28L TFC. UPON MISSED APCH AND INTERCEPTING NOW 28L LOC 108.9 ONLY USING AUTO THROTTLES; AT OM; AUTO THROTTLES DROVE THROTTLES TO GAR PWR ON ITS OWN. ALL AUTOMATED SYS WERE DISCONNECTED AND THE REMAINDER OF APCH AND LNDG WAS UNEVENTFUL. SUPPLEMENTAL INFO FROM ACN 199481: AT ABOUT 800 FT WHILE FLYING A MANUAL ILS WITH SNOW ALL OVER THE GND THE CAPT STATED HE HAD THE RWY OUT HIS L SIDE. I HAD DRIFTED SLIGHTLY L ON THE APCH BUT ELECTED TO LISTEN TO HIM CAUSE OF THE PREVIOUS ELECTRONIC DIFFICULTY WE HAD. ALSO I WAS INSIDE THE COCKPIT FLYING MANUAL WITHOUT THE RWY IN SIGHT. IT WAS GOING TO TAKE A LOT OF EXTRA EFFORT TO GET TO THE RWY HE POINTED TO AND AS I MADE A L TURN AND DSNDED THE APCH CTLR INSTRUCTED ME TO MAKE AN IMMEDIATE R TURN AND CLB. SIMULTANEOUSLY I WAS THE FIRST TO RECOGNIZE WE WERE NOW HEADED FOR 28L. WE NEVER LOST SEPARATION WITH A COMMUTER ACFT FOR 28L BUT DEVIATED ENOUGH FROM THE 28L LOC TO BE GIVEN A GAR BY APCH CTL.