For some reason, Cisco products have always kind of reminded me of Unix.
A huge pain to get configured at times, but, once configured, you tend to forget about them, because they just work.
Anyway, good luck with this, sounds like an interesting if somewhat frustrating problem.
In my own tech world, I just got done fighting with Backup Exec, because it decided to go from 122 MB/min throughput to 1 MB/min throughput when backing up.
There was no apparent reason for the problem to occur, and what seems to have resolved the issue was upping the sync rate on the SCSI controller. I upped it to the maximum, versus what the tape drive manufacturer said it should be. Uggh.
For some reason, Cisco products have always kind of reminded me of Unix.
Probably not by accident either - there is a strong unix culture within Cisco.