Yet another update: my co-creator says she can start a topic or thread just fine. She can reply to the first post, but cannot reply to any other posts in the thread. She simply cannot type any text in the box.
Update: IE 11 on Windows 7 appears to be working. However, last night I was unable to use the visual editor on my Windows 8 machine. My site co-creator has experienced problems with Windows 10.
