Denon MC2000

A) There is always the potential of actual hardware failure
B) Have you tried using the controller with just the laptop (and a headphone plugged in) and play with it for a prolonged period of time (say an hour+) to see if you have the same problems. If not, plug in all the things you normally bring to a gig and try again to see if the problem occurs.
C) If you are in the USA, I am aware (also from friends that do a lot of live sound engineering) that power in the US is a LOT worse than it is in our part of the world (northern europe).
D) An audio 8 will typically have a lower USB load than an MC2000.
E) Smoke machines can be pretty bad. The moment they switch on or off can cause spikes and drops in the voltage
F) In the US typical amperage of a 110V outlet group is 15A or 20A. This equals 1650 to 2200W. Now if you add up what you are bringing you can see you are getting close or over that number. Now typically an overload in consumed power would lead to a circuitbreaker kicking in, but it’s not unimaginable that the overall power drops a bit.
G) Use of extension cords can also lead to loss of power (both in Wattage as in Voltage).
H) Although not the best option (soundcards preferably get hooked up directly to the laptop), have you tried a powered usb-hub?
I) Usually two adjacent USB ports on a laptop share the same power, if you have both in use with USB-Powered gear (like a controller and hard disk), you might run out of power.

Just a few thoughts on what could be potential problems.

Anecdote: Early july I had a fundraiser kind of gig in the courtyard of a medieval castle. I have played there many years without problems (MC6000 controller, MacBook Pro, Traktor first, later Mixvibes Cross). Pretty hefty PA, quite some (LED) light fixtures.
This year I took my power from a different outlet. I had an outboard rack which has a voltage meter and it kinda went up and down between 210-220. 220V was the old standard. Nowadays it’s 240V.

I had my big setup with me, the same MacBook Pro, but with two Denon DN-SCX2900 midi/mediaplayers and a Denon DN-X1600 mixer.
My software crashed, my sound went bad on one deck after a few tracks, my players crashed or hung, I ended up playing only CD’s all evening. Not a major disaster, but pretty uncomfortable.

The gear is now setup at home and not a problem at all. Played three hours straight without a hitch.

This shows that there are too many factors in play to say “well I used it with gear X and never had a problem, so gear Y shouldn’t have a problem either”.

Seriously? I have lived here all my life and power is pretty stable at around 240V with very little spikes and surges.

The only bad experience I had was in the medieval castle on a group that was probably powering other stuff and connected to a 30m extension cord that wasn’t thick enough for the job.

I have been to many places in the US over the years and have experienced unstable power in most places I went to (Florida, Texas, New Jersey, New York, Virginia, California, Oklahoma, Chicago to name a few).

Granted, I never did measurements, but I did have a few colleagues who did a lot of shows in the US as I said and they were always complaining about the power grid.

This is strange, because you said you are using a different power source – do you mean a different wall outlet, or is it a completely different circuit?

Also, what are you using to distribute your power? You might think of looking at a PDU instead, or replacing your power strips to see if that solves any issue.

Last thing that I would check since you said that you ran your laptop off a different power source, monitor your laptop levels while spinning. Make sure it is not running out of CPU or memory. Although, it does not sound like this is the case if the problem is happening when you switch your smoke machine on.