Lights randomly flash
A possible explanation: there is something wrong (or intentional) about your wiring such that there is a very weak (high resistance) path for current bypassing the switch.

In some designs of power supplies, the small current will charge an internal capacitor, and when there is sufficient charge it will assume it's been turned on and start supplying power to the LEDs — which then immediately discharges the capacitor, resulting in the brief flash you see.

Perhaps your light switches are illuminated, or they have some sort of special function beyond being a simple mechanical toggle switch. One common reason for this sort of leakage is devices inside the switch which need power and (since there may be no neutral wire at the switch, at least in US wiring) get it by letting a small amount of current through the switched circuit.