UNCTLABLE PRESSURIZATION. EMER DSCNT AND UNEVENTFUL LNDG. NO POST FLT INFO AVAILABLE.

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AT CRUISE; BOTH PLTS DETECTED A SUDDEN SURGE IN CABIN PRESSURE VIA THEIR EARS. A VISUAL CHK OF PRESSURE CTLR; CABIN ALT; AND CABIN RATE OF CLB SHOWED A 1000+ FPM CLB FOR 1-2 SECONDS; FOLLOWED BY A RETURN TO ZERO FPM. CABIN ALT WAS 7200 FT. A FEW SECONDS LATER; THE SURGING STARTED AGAIN WITH THE RATE OF CLB INDICATOR PEGGING AT PLUS OR MINUS 4000 FPM. CAPT SWITCHED THE CTLR TO 'STANDBY;' WHICH SEEMED TO WORK FOR A FEW SECONDS; AND THEN FAILED WITH CABIN CONTINUING TO SURGE UP AND DOWN. CAPT SWITCHED CTLR TO MANUAL ALTERNATING CURRENT POS WITH NO EFFECT. OUTFLOW VALVE SHOWED FULL CLOSED; BUT CABIN ALT CLBED IN EXCESS OF 10000 FT. EMER DSCNT WAS INITIATED WITH CREW AND PAX ON OXYGEN (PAX MASKS DEPLOYED AUTOMATICALLY). LEVELED OFF AT 10000 FT MSL. NO EXPLOSIVE DECOMPRESSION OCCURRED AND ACFT FLEW NORMAL THROUGHOUT DSCNT; APCH; AND LNDG. NO STRUCTURAL; ABNORMAL LIGHTS (DOOR OPEN); OR FLT CTL PROBS DETECTED AT 10000 FT MSL. PRESSURIZATION CONTINUED TO SURGE WITH CREW UNABLE TO CTL OUTFLOW VALVE; EVEN WITH MANUAL DIRECT CURRENT SELECTED ON PRESSURE CTLR; AIR CONDITION/PRESSURE PACKS TURNED OFF TO PREVENT FURTHER SURGING AND INCREASE PAX COMFORT. UNEVENTFUL LNDG AT DENVER INTL. NO CREW OR PAX INJURIES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR FO HAD NO DEFINITIVE FURTHER INFO OTHER THAN THE PRESSURIZATION CTLR WAS CHANGED IN THE ACFT. HE SAID THAT HE HAD HEARD THAT THE ACFT HAD ANOTHER PRESSURIZATION PROB SUBSEQUENT TO THEIR EVENT; BUT KNOWS NOTHING MORE. IN THEIR PROB; THEY COULD NOT GET CTL OF THE OUTFLOW VALVE IN ANY POS; EITHER EMER ALTERNATING CURRENT OR EMER DIRECT CURRENT.