How Can I Troubleshoot Bluetooth Hardware?

Problem

Item below mouse pointer or cursor has uncommanded mouse down or selection mode. Mouse down repeats randomly on and off. Similar effect with keyboard by uncommanded selecting of text. Condition repeats over and over until Bluetooth in System Preferences is turned off.

Conditions

iMac mid 2011, Yosemite, 16 GB RAM.

Does not appear from cold start. Appears within 5- 10 minutes of power on and remains while power on.

Demonstrated to affect Apple Wireless Keyboard, Apple Magic Trackpad, Apple Magic Mouse, and Logitech USB Mouse (yes, even the USB mouse exhibits odd behavior when Bluetooth is acting up.

Condition goes away when Bluetooth is turned off in System Preferences. Computer operates normally with Bluetooth off.

Condition appears in safe mode also.

Condition is not OS Version dependent. Appeared in tests booting from external drives with Mavericks and Mountain Lion.

Apple Hardware Test (Option D on startup) extended testing accomplished multiple times over the past 2 weeks. One failure reported in early test, but never repeated:

4MEM/9/400 000 00 0x88437618