Hi George,
I've never figured out what actually caused this problem and in typing this answer, I'll discover if I still have the problem.
I've recently made a few posts on
www.highdeforum.com - which uses the same forum engine as this - and didn't get a problem - but I was useing their 'quick post' feature which doesn't give you all the fancy editing capabilities. I'll have to try a post there with the full response.
So, I experimented by typing enough to fill this dialog box and as soon as the scroll bar activated on the right, the problem showed up.
