2003 STS - navigation radio problems

i have a weird problem. when i put a cd or a dvd in my navigation radio it says no disc inserted. but the navigation cd works fine.i have no idea why it doesnt recognize nothing except the navigation cd. also sometimes when i start the car up the radio either:

-the screen doesnt come on but the radio plays still
-the screen doesnt come on and the radio never plays
-the screen comes on and the radio plays but the touchscreen itself along with the buttons doesnt work

along with this the controls on the steering wheel works when the radio works tho the screen isnt on or isnt active and sometimes i can use the command button on the steering wheel to tell it to play cd changer and it will but sometimes it doesnt plus the biggest thing in all this is if i unlock my door with the remote and open the door if the door chime doesnt come doesnt ding when i stick the key in while the door is open i know 9 times out of 10 the navigation radio wont act right either. can someone tell me what could possibly be the problem? ive seen the door module fault and the navigation radio fault when i pulled codes but i dont know how to pinpoint which area i should focus on. thx in advance for any response