Exchange Server 2003

I'm not sure if it's an exchange issue or if it's outlook, but just recently as our users are sending out meeting request's the date and time for the meeting is showing up as the current date, and the time is rounding up to the next even hour from when the request was sent. Ex: I send a request out to meet next month at 5:00, the recipients receive the request for today at the next closest hour. After trying to duplicate the problem it seems that it is only happening when sending to a group (exec committee), and not when sending to an individual. It has also been when sending "on behalf of". Were running exchange 2003, outlook 2007, Symantec SEP 11.5, and XP Pro. All SP up to date. Thank you in advanced for any suggestions.