I think it started about the time I updated to EE 2.8, but I'm not sure. It could have been a Wygwam update too. In any event, my channel entry form featuring a Wygwam field has stopped working when certain characters are used. Here's one that reliably causes the problem:
& # 3 9 ;
(Spaces added because it was converting to the ' character when posted.)
Basically, I submit the form and it just works and works and works, and eventually just loads a blank white page with no content and the entry isn't added.
There are no problems when adding an entry through the admin, however.