I can't find a Delete button here, oh well, sorry! I ended up with problems which only some GPS apps, and mostly Navigator seemed to be giving me, but it turned out to be my use of Tasker, where I had included an exit task to shut off GPS every time I exit an application. It turns out that Tasker, in such a context, will shut off GPS not just when you shut down an application, but every time that you use the HOME button to use a different app while Navigation (or presumably other GPS apps, although this never seemed to happen so quickly as when you exit Navigation. I am learning that some radio functions, particularly those which you use quite a bit, aren't worth the stress of neurotically shutting down just because they aren't in use. Although I cannot vouch for leaving Bluetooth on all the time, it's been observed by others that GPS won't run down your battery, so long as you don't leave GPS apps running endlessly in the background.