I had the original post on this thread and wanted to follow up with my findings. A couple of people mentioned antenna problems along with the radio problem and since my Z had a manual mast installed at some point, I thought maybe they're related. I replaced it with a power antenna (new, adaptable, but not Nissan original) from Ebay. Afterwards tested the unit and the radio turned off/on just dandy which it had never done in the 3-4 mos. that I have owned it. Tested it further about 20 times, no failures. Hooray! right? Got in the car a day later tested it again and it didn't work properly. Had to insert a cassette tape to get it to power up.
Conclusions? none really, maybe I was onto something, maybe it's all coincedence.........dunno. I appreciate the tip, but for me it ain't worth removing and sending to wildbill for repair. Also,I really don't expect him to hurt his potential income by divulging the answer. It does bug me not knowing the cause.
Dane