I had an issue once with a 500 € bill, but that was probably a bit my mistake. We bet that it could hardly catch fire. Actually, it easily does. With an edge slightly burnt down, it was still accepted at a bank later. (But not the petrol station we wanted to use it originally)

Given 100$ is really quite a small amount to other bills, it actually does astonish me. Here in Switzerland, 100 CHF (around 115$) are one of the most regular bills to be seen, and accepted everywhere. Even 200 CHF (230$) are usually not that much of an issue, at least if your bill is over 100 CHF or so.. the only issue is with 1000 CHF bills (1150$) - they are usually double checked at banks and are not widely accepted, but I do understand it at this amount.

Is the security on those 100$ bills really that low? Maybe the US really should swap it's old style bills against some more secure yet colourfull European style money if they have so much issues with it.