Electrical question

I have an 07 Durango that came with the fully loaded sound system. However, i think before the owner sold it, the radio was stolen because the stock navigation unit was replaced with a Pioneer Avic-N3. The problem is, almost every other time you get in the car, the radio will not play ANY audio. But if you turn the car off, open the door, and/or just wait a while itll work next time you turn it on. Another thing, sometimes (almost every time actually) when i drive at night the dash lights will not work or turn off while driving..what the hell is wrong with my car? Is this radio interfering with everything? I was told by my mechanic that he couldnt read any fault codes from the OBD port, possibly due to the aftermarket stereo and a crappy wiring job on it.

So is anyone experiencing anything like this? I'm thinking of getting rid of this thing before it causes any more problems. Its too bad cuz its a good looking, fast, and well-designed truck..just not made well apparently.