Good points, everyone. I'm still trying to isolate the potential source by re-installing the select apps, one by one, and restarting the phone after each new app is installed and then opened up. So far, I've re-installed 8 apps. I'll resume in the morning.
Well, I reinstalled most of the third-party apps I had, plus a number of additional ones, with no apparent problem.
Then I turned the device OFF overnight, wondering if I would have a problem when I turned it back on this morning. Lo and behold, I had a repeat of the display screen seizure that prompted this thread in the first place.
So I did another hard factory reset, and appear to be no closer to a resolution of the problem.
I'll provide another update when I have something substantive to add.
Well, I'm on the verge of returning this phone, despite my desire to love it.
Thus far, I have invested many hours in trying to get my K1 up and running to my satisfaction, to no avail.
I have had to perform numerous soft resets and four hard/factory resets and still no satisfaction, all because something (still undetermined) associated with downloading and installing third-party apps (from the Google Play Store) so destabilizes enough of my device's operating system (or at least it's user interface) as to render it largely unuseable.
All that being said, unless I have a change of heart, I will likely return this to Amazon and try one more time with another K1. And if that fails to pass muster, I'll send it back as well, with instructions for BlackBerry to email me when they are grown up and ready for the big leagues.
Last edited by Vaughn Mises; 07-09-17 at 12:41 PM.