Since you replaced the processor I think you are going to have to either start replacing the VM card and the expansion mods as well as the 5 slot carrier (one at a time!) or remove everything, operate with just the processor and start adding things back one at a time. I suspect it will operate just fine with just the standalone ACS.
That is where I would start looking, I seriously doubt a phone would cause this. This is also why, if you are going to service and install these systems you are going to need to have spare equipment on hand or at least be willing to purchase same. That's the only way you are going to diagnose weird problems like this.
-Hal
