I have a 7206 running 12.4(3g) IOS, it has a PA-MC-8T1 in slots 3 and 4, and it has a PA-2FE in slots 1 and 2. Intermittantly, the T1's connected to the PA in slot 4 lock up - the only way to recover is to reboot the router. We have already replaced the PA in slot 4. When I say the lockup is intermittant, I mean it can go anywhere from 2-5 weeks between lockups. It just went 5 weeks and 5 days since the last one. Any ideas on what I can do to fix this? I have opened a TAC case on this, but they have not been any help.