Need advice: Pioneer DEH-4390UB

I installed this system in my Skoda Octavia in September 2011, replacing the older HU which didn't have an AUX or USB provision. Almost immediately after installation, I faced one glaring issue which continues to plague me today. The system suddenly powers off - goes completely blank - and comes back in a couple of seconds. When this happens, all presets and personal settings revert to factory settings. 1. This happens all of a sudden, and doesn't get triggered by any specific operation in the car (turning on headlights, AC, pressing the horn), or by any road condition (bumpy road, speed breakers, etc.). It happens at any speed. 2. Frequency of occurrence varies. Its happened twice in a 15 minute journey, and not even once on over 2 days of driving. Twice, the HU has powered off and not come back on. The first time, I took it to the retailer, who checked out all the wiring and said the clip supplying power was loose. He fastened the clip to the speaker leads clip with a plastic harness and re-attached it. Result: The problem disappeared for a week or so and then returned sporadically. Two weeks ago, the system powered off and refused to come back on for the second time. I took it back to the retailer and pushed him to send it to the Pioneer service center for a thorough check up. Because of the rush at the service center, the system was accepted by the service center only yesterday. Today, the service supervisor calls me back and tells me that nothing is wrong with the system. I am pretty desperate as neither Pioneer nor the retailer seem to know how to fix this issue. Any suggestions from the ICE maestros here?

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