I am using Firefox. I have experimented with Internet Explorer and this problem does not happen there.
When I type “watch” into a forum post it vanishes as soon as a press space, period, comma, exclamation, or question mark. Other characters are safe, so for example because I ended the word with a quotation mark earlier in this post it did not disappear. If I had tried to type it without the quotation marks, then it would have looked like this: “When I type into a form post it vanishes.”
I can also type watcher, watching, etc. I can also type things like Watch, wAtch, and so on, but when it is exactly w-a-t-c-h in all lower case letters, it just disappears as if I’d never typed it at all.
Is this only happening to me? Are there any other words that do this? What could explain this behavior? It seems somehow deliberate.