I discovered that this is a known problem. I don't know why it happens but apparently it has something to do with incompatibility between this software and the newer php software. The forum software is something that I can have updated but the php software is controlled by my isp.
Interesting it is, that if you reply by clicking on "quote" or "quick quote" or "quick reply" the intended text reappears, albeit somewhat garbled.
I will attempt to fix this as soon as I'm able to do so.
" Not all those who wander are lost ! "