Migrated a SV8100 to a SV9100. Every 3 to 4 months the system locks up. No alarms, blade status is normal, reset fixes the problem. Instructed customer to keep a record of what happens. Customer called today and said it happened again. Digital phones were locked up, onsite VOIP phones were fine. Display on the digital phones said "page from kitchen" which seems to be it happened after a phone made a page. Resetting the digital phone would just say "Initialize" and would not come up. Could access Webpro fine and he reset the system from Webpro. No alarms, blade status was normal. Tech support said it may be something with the network but that seems to be fine. In over 20 years experience with NEC I have never seen a bad CPU. Any suggestions would be greatly appreciated...