I have a 1999 E300 TD. Intermittently, my front power windows, power seats and power mirrors all stop working - all at the same time.

I spoke with the owner of another E300 TD and he told me he had the same problem and solved it by disconnecting and reconnecting the battery. I did the same and the windows, seats and mirrors all worked again. But every 5 to 6 days, it happens again and I have to disconnect the battery to get the windows, mirrors and seats to work. It's very frustrating. Any idea what might be causing this?

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1999 E300 Turbo - 112K miles
1987 300D Turbo - 89K miles
1984 190D 5spd - 152K miles
1969 220D Auto - 170K miles