Office A: 7400 v4.60b with PRI incoming service and an OAS card for MGIs. It is SPNetworked to Office B:

Office B: Gets calls from Office A. Once every 2 months or so their system starts to 'wig out' until I reboot it. When it starts they'll answer their phone but the call is still ringing on the very same phone they just picked up the handset on. After a couple rings, their phone stops ringing and they're patched through to the caller. It gets worse and worse and worse until I usually remotely reboot it.

It sounds like a routing loop is spirling down the system at Office B? I've called in the local POTS plugged into Office B and their doing the same thing.

Processor getting chewed up?