Teaser not being generated

I am building a community site and trying to use TinyMCE text editor. We're having a lot of problems with several teasers not being generated. I'm certain it's got something to do with TinyMCE and I suspect that it has something to do with people copying from MS Word. But when I look at the HTML code, I don't see any code that should be creating any problems. Just normal stuff - p tags, i tags, etc. I'm not sure if this is a code or configuration issue.

I'm stumped - any help very appreciated. Thanks!