I have some sort of strange problem. I know little about plumbing, so
I have no idea what to do and I'd prefer to avoid calling a plumber. I
will if I have to, but I'd like to try to troubleshoot it myself.

Beginning sometime this summer, once in a while the pipes in my house
would vibrate for a bit. This was usually when I had the water running
outside and would then start some laundry or something like that. The
vibrating was usually short-lived and it didn't happen very often. For
some reason, the problem has gotten rapidly worse this past week. Now
the pipes start vibrating like mad anytime something is using water.
Flush the toilet, turn on the shower, start some laundry...it's awful!
The pipes are *seriously* vibrating. It sounds like someone is trying
to tunnel into my house using a jack hammer.

Here's what I know about the house. It was built in 2001, so the
plumbing is relatively new. It has a pressure arrestor of some sort
that was set before we moved in. It has an ominous warning note not to
mess with it, so I haven't.

Where should I begin looking?

Thanks!