Mitch its definately a clash with the assories and +12 perm line.
Seems like your AC and clock's +12 perm volts line is not connected or is wired incorrectly with the assories.... So when its off the +12volt goes away...
I wired my HU the wrong way around and when I turn off the car the AC and clock would reset. Then I rewired it and it worked fine.
ALso check fuses if they have somehow blown? but then again u wouldnt get any power if they were.