I'm posting this issue along with the (simple) solution to save others unnecessary stress.
After using AL V successfully for months, it starting crashing after an hour or so, usually in the middle of a gig. Symptoms were the keyboard suddenly going dead. Required unplug/re-plug/re-initialize of the keyboard (Keylab 61 Essential, but not important), and then a restart of AL V. Sometimes, AL V would also freeze, requiring a three fingered salute to get to the Win Task Manager to close the frozen AL V. Occasionally required a Win reboot also. The it would run fine for another hour or so and crash again.
For reference, I use both MS Surface Pro 4 and Surface Pro 7
Particularly frustrating for me as I've been working IT solutions of all kinds for a living for many years, and could not figure out what could have possibly changed to create the problem. Turned out to be a simple solution:
I was connecting my digital devices (Keylab 61, a 2 channel audio interface, and a Logitech universal wireless mouse controller dongle) using the single Surface USB port and and small USB port extender (generic Amazon), powered from the USB port. After much navel contemplation, I took a USB cable and connected the USB port extender power input to the Surface power brick (they come w/ a built in USB power port).
Problem solved. No more "crashing".
I'm guessing that the internal USB port provided just enough power for everything to work ok until it probably heated up after an hour and suffered enough of a voltage drop to lose the USB logical connection (because nothing appeared to power down). The restart/reboot process gave it time to cool down enough to let everything work for a while, when it failed again. Probably age related, as it worked fine for months.
SO, when using multiple USB musical instrument-type devices on a single USB port, assume there probably isn't enough power in the port and add external power, especially on a small system like a Surface, which is essentially a Win tablet with a keyboard.
