No matter how good a surge protector is, it only protects against voltage spikes and spikes are only 1 of the 5 common power problems, which are...
- Voltage Spike: a sudden impulse of very high voltage (probably the most common problem and certainly the most widely marketed)
- voltage surges: voltage rising to over 125 or so volts for an extended time
- power dropouts momentary power loss generally far less than a second (probably more common that you might imagine)
- brownouts: voltage falling to under 90 or 100 volts (California in the summer)
- complete power failure
Apple uses sophisticated switching power supplies (even the little iPhone chargers are crammed with circuitry) that will generally prevent system damage from voltage surges or brownouts. That still leaves you vulnerable to dropouts, power failure, and to a lesser extent surges and brownouts.
A
surge protector, no matter how good, generally only protects your system from voltage
Spikes and maybe extended surges (read the specs very carefully). Surge protecters are the first line of power defense and the most vulnerable because a truly major spike, like a nearby lightning strike, will often (usually?) fry one — but you may never know it has given its life to protect your computer until there is another major surge and it doesn't work.
Some high end surge protectors (read that as expensive and heavy) provide
AVR (Automatic Voltage Regulation) through the use of toroidal coil transformers (these are what makes them so heavy) so that given a voltage input of anywhere between 90 to 130 volts will maintain a relatively constant 120 - 125 volt output. The Toroidal coil transformer also has what could be described as a
flywheel effect that suppresses short dropouts. Such devices are difficult, if not impossible, to find these days however.
a
UPS (Uninteruptable Power Supply) with its built in battery backup provides protection for most power conditions but depending on how it is designed and the quality of the switching circuitry it may be vulnerable to dropouts and/or if you are in a situation or area where the power is erratic you may find the battery has run down just when you need it most. The optimum solution is a UPS with AVR, which makes most swithovers to battery power unnecessary, not only extending run time but also extending battery life.
In the situation Jon described a
dropout would be the most likely power related suspect, and your Surge Protector is useless in that situation.
NOTE: Because power companies try to minimize disturbance to their customers, dropouts are often the result of late night repairs and switchovers.
Mind you I am not saying I think that is the problem, but if I were
rounding up the usual suspects dropouts would definitely be on my list.