Problems with head unit's clock!!!

[nittanys1]

I have a Sony mini disk head unit and have had it in two cars. It was in my 95 accord and I had it installed by the people who I bought it from. Well my g/f TOTALED that car and with the insurance money I was able to get my self the car you see below....

Well my question goes something like this. When it was in my 95 the clock matched the one on my dash and when I had my lights on the dimmer (when set on auto) on my radio worked when I had my lights on. Well now that I had it reinstalled by the same place (different installer) The clock always seems to get off from the on in the car. I noticed that when I start my car up the head unit goes off for a few seconds then comes back on, and this is what is causing the difference in times. Also the dimmer doesn’t work with my headlights.
So I was wondering if anyone knew what I could possibly do to get things back to the way they were.