Its not the parking brake wire. I disconnected it. Others say it could be the car battery. I just got my less-than-a-year-old battery tested and it is perfectly fine. Plus, if it was the battery, it would have done the same thing in safe mode. In safe mode, the unit works fine for me, without GPS abviously. It could be 3 things:
1) The GPS antenna, because when I unplugged it, my stereo works fine, obviously without GPS.
2) The Head Unit, GPS part (not radio, ipod, usb, sd, cd, dvd, hd or any other "d").
3) Since most people, like me, got this problem around 2 weeks after installing the unit; and it first happened when using GPS, I would say it has something to do with sofware, or programming. Maybe data got built up somewhere, and the system got confused everytime it's trying to read your new location at a higher speed.
Here is what I suggest, which is what I am doing. Try the least expensive way first. If the unit is still under warranty, have the person who sold it to you or Pioneer send you a GPS entenna. If that does not work, then have the unit replaced. I would not recommend you to mess with hardware, software or programming, etc...Unless you really know what you are doing and if the unit is no longer under warranty. Most, if not all, companies will void warranty if hardware and or software have been compromised. That's my two cents. And please try everything at your own risk. Eveything that was said it my personal opinion, and I must not be held liable.