Hmmm, really hard to say, I am testing in on 3 different (completely different settings) servers without any problems, really no idea where can be the problem (if in Joomla! settings - text filters, or in some system plugin which can somehow clean the input or in database settings)
I think, some specific tests directly on the server must be done
(to get info about the input which should be stored into database before storing it
)
Jan