Am I using the wrong mosfet to drive an inductive load?

I have a linear solenoid (a JF-1039B), rated 12 V at 400 mA draw.

I'm trying to switch this with a uxcell BUZ91A, which is rated for 30V 60A.

I am switching the mosfet with 5V from a 5V Pro Trinket digital pin; and switching the 12 V (-) lead to the solenoid.

I tried a quick sketch for 500 ms off; 500 ms on, just as a test.

Results: The solenoid appears to be receiving a high-frequency signal, as it ends up just sort of vibrating a bit without fully actuating. Meanwhile, my second computer monitor goes black (!) when I apply the 12V power (which I only plugged in after the program had loaded onto the arduino).

Now, needless to say I unplugged the 12V power within 2-3 seconds after plugging it in, shocked (heh) at what had happened. My second monitor turned right back on, no issues.

After sitting here for a moment, and deciding that I had hallucinated this weird coincidence of events, I replicated the problem. Vibrations, monitor off, monitor on, all over again.

I don't seem to have broken anything, except maybe the mosfet.

So, uh, can anyone help explain what the heck I did here? If power had gone back through my FTDI cable, I'd assume I would have blown the arduino and a USB port, at least. But that didn't happen.

The 12V supply is a wall-wart, plugged into the same mains circuit as my computer / monitors (eg on the same circuit breaker). But nothing else happened; there's a lamp on that circuit too with a fluorescent bulb; no change seen there, nothing wrong with the monitor or computer...

Here's a pic of the demon circuit. I tried two different mosfets, as shown.