We have a Nortel 81C with 6 network groups. Yesterday morning the sytem started generating ERR5425 codes. (Buffer to the PRI (QPC720) hardware has overflowed.) The T1 circuits involved are not QPC720 cards, they are DDP cards. Additionally, callers are complaining they are getting dead air when they try to call out on these T1 circuits. I disabled T1 loops 110&111 and unseated the card. Now the errors (err5425) are being generated against T1 loops 108&109. Any ideas on how to correct this problem.