Tracing down short pauses

Every couple of days my computer locks up for about a minute. It doesn't happen all at once, my mouse and keyboard lock up, except for swapping between windows, and then what I'm playing on my iTunes stops. And then everything starts again, queuing up my commands. I open up my Console and look for something interesting at the time, but don't know what to look for.

Since I can't repeat the problem, I'd like a clue about what to look for, so I can cut and paste it to show an Apple Genius or someone else.

I don't see any sign of permanent problems, and have had Malwarebytes do full scans on my computer. All of my software is kept current. (macOS 10.13.3).