Weird punctuation in OWA messages

We just added a Win2003/Exch2003 server at a client?s office. Whenever they send emails through OWA from within the office, the recipient receives the message with a question mark preceding the body of the message and random punctuation and wing dings substituting all previous apostrophes. Outside of the office the same thing happens but only rarely. It does not seem to be user specific. It appears that all of the affected users have Office XP but various versions of Windows. Anyone have an idea what is going on here?

Thanks in advance.
Net-Tech