N2 nav problems, freezing up

I have the AVIC-N2. I am having a problem with it switching to NAV mode. I have done the reset on the front of the unit.  Forced software flash and cleared the memory.

It does not "switch" navigation mode when I insert the Nav DVD. However if I put the dvd before doing anything else it will read the nav dvd and allow use of all buttons. The speedo and gauges also do not come up...only a screen with the regular background.

If I take out the nav dvd (while it is actually working) and listen to a cd...when I try to put the navi dvd back in it does nothing. The when I click the AV button it will go to whatever the nav screen was previsouly on. But will not change and none of the buttons work (screen or unit) The map will not zoom, move, or move along the road. It pretty much freezes up. However I still have all functions for the rest of the radio. FM/AM radio, XM tuner, and TV tuner all work.

Normally when I insert the Navi DVD you can hear it whirling around reading it, but now it does not do that. (only time it does is when you first boot it up)

GPS antenna signal is full; dvd is not strached at all.

So in conclusion the navi only works when the radio is turned on with the dvd in. After that NAV does not work, map does not move; Nav screen freezes whether on the menu, map, or gauges. Does not read touch screen buttons or unit buttons. However function of buttons/touchscreen of the rest of the unit work. (CD/XM/TV)

It works if the nav dvd is the first in when the system is turned on....once i take it out the unit needs to powered off to read the nav dvd again.

Thanks,
Kevin

It seems as though the memory stays full or doesnt work at all.  It will not switch to memory nav mode.  I tried a backup mempory clear.  It work one time with memory nav mode.  After that it did not work. 

Can I clear out all those other options on the service screen?  Such as the gps memory one?  or clear any one those files?