No way to exit Settings app on T58A

[CFortC]

With latest firmware update to my T58A (58.85.0.5) I find that there is no way to exit the Settings app. It seems crazy, I realize. The same applies to the File Manager app. However, the apps which interact directly with phone data such as calls, contacts, and messages retain their little left arrow icon in the top left-hand corner, enabling exit back to the main phone screen.

This problem is persistent over several firmware version downgrades and upgrades. It's like the Android section of the phone is busted.

Anyone else seen such a syndrome? Any ideas?

Thanks in advance for any help.