Lockup in pre-pro caused by line voltage dip?

My Sherwood-Newcastle P-965 occasionally locks up right after power on. The front display appears normal, but none of the controls work and no sound is produced.

I was going to send the unit in for diagnostics and repairs, but then I noticed that sometimes, when switching on the main amplifiers, the UPS battery backup for my computer, on the other side of the living room, will beep momentarily, indicating that line voltage has dropped due to the inrush current of the amplifier powering up. I wondered if the DSP-based pre-pro, which is basically a computer dedicated to audio processing, was suffering a similar voltage drop, causing it to malfunction. Because my amplifiers switch on after the P-965 (in order to protect the speakers from loud thumps or clicks), any voltage drop caused by the amplifier powering up could indeed affect the P-965. At the time, my audio gear was plugged into a Monster Power HTS850 Power Center, but this only suppresses voltage spikes; it does nothing about voltage dips. So I plugged the P-965 into a separate UPS battery backup. Voila! No more lockups. The new UPS beeps momentarily every time I turn on the amplifier, so I know that the P-965 would be seeing a voltage dip without the UPS.

Has anyone else had a similar experience?