Cisco 3662 Router T1's "Drop Out of Bundle"

[BaldFromStress]

I am trying to resolve an issue with a Cisco 3662 router (3600 platform) housing 4 active T1 controllers (PRI 2CT1-CSU) and a 16 port ethernet interface. The issue is that the T1 circuits intermittently "drop out" of the configuration bundle then mysteriously come back up, sometimes after weeks or months. They are all administratively up and pass loop-back tests to the CSU. It is not frequent but it happens often enough to create havoc with the network monitors although the users are not affected (at least from their perspective, although bandwidth utilization is reduced). Is this likely to be a configuration issue or is the main board crapping out? Will this kind of thing happen if the onboard memory is pushed too far? Has anyone ever experienced this before?

This is a locally managed device (cannot telnet because of security configurations) and is physically 3 hours from my location, so access to scripts is limited.

Thank you

 

[artesian2000]

Check for IOS bug issues. Had something like this running on an old 12.1 load.