Adding my data point. Wasn't able to log in starting about three weeks ago (got the inactive account message). Waited a few days and sent a note to customer service. Took them two weeks to get back to me with the same shutdown message others have posted, even though I hadn't actually violated any T&Cs. E-mailed back for the specific violation I committed and was told I was shutdown and that was it (response was in less than an hour). A few days ago, I did send a PM to the employee who showed up in this thread, but I haven't heard back.
I was using the click though old messages method to increase survey volume. I have to assume that was the cause, since I was compliant with all the T&Cs. Now I'll have to figure out another way to keep a couple of my FF accounts active.