B737-300 ACFT DSNDING TO A XING RESTR WITH FMC PROGRAMMED. VNAV SELECTED TO GET ON DSCNT PROFILE WHEN CAPT ENTERS DEST RWY AND FO OBTAINING ATIS. DISTR AND MODE CHANGE CAUSE ACFT TO BE 900 FT HIGH AT RESTR.

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AT FL370 CLRED DIRECT TO HAR VOR. NORMALLY; ZOB CLRS ACFT TO CROSS COFAX INTXN AT FL250. IN ANTICIPATION I (PNF) BUILT A FIX ABEAM COFAX (40 MI W OF HAR VOR). HOWEVER; ZOB CLRED US TO CROSS 45 MI W OF HAR AT FL250. THEREFORE; I REPROGRAMMED THE FMC. AT THE SAME TIME; FO STARTED A 1000 FPM RATE OF DSCNT TO ENSURE MAKING THE RESTR. WHEN THE FMC COMPUTED THE DSCNT; IT SHOWED US TO BE BELOW THE PROFILE; SO THE FO SELECTED VNAV TO ENSURE WE WOULD INTERCEPT THE PROFILE AND MAKE THE XING ALT. I VERIFIED THE AUTOPLT WAS IN LNAV AND VNAV. I THEN BEGAN TO SELECT APCH PLATES FOR THE ARR TO PHL BECAUSE THE FO SAID HE WAS GOING TO GET THE ATIS. WE BOTH NOTICED THE FMC SHOWED US 3300 FT HIGH ON THE PROFILE AND THE VERT-SPD LIGHT WAS ON AND WE WERE ONLY DSNDING AT 1000 FPM. THE FO IMMEDIATELY DISCONNECTED THE AUTOPLT AND EXPEDITED OUR DSCNT USING SPD BRAKES AND INCREASED AIRSPD. DUE TO FREQ CONGESTION; I WAS UNABLE TO ADVISE ATC WE WERE HIGH; BUT IT APPEARED WE COULD JUST MAKE THE RESTR; ANYWAY. WE CROSSED THE 45 DME APPROX 900 FT HIGH AND WERE LEVEL AT FL250 WITHIN 1 MI OF THE 45 DME FIX. OUR TCASII SHOWED NO TFC WITHIN 10 NM EITHER AT OUR ALT; OR ABOVE OR BELOW US. UPON REFLECTION; AS THE PNF; I SHOULD HAVE GOTTEN THE ATIS WHICH WOULD THEN ALLOWED THE PF TO MORE CLOSELY MONITOR THE PROGRESS OF THE FLT AND MOST LIKELY WOULD HAVE NOTICED THE PROFILE DEV SOONER.