I have a particular user whose Outlook is acting up. Whenever he accepts a meeting invitation from a specific person, the reminders get turned off in the calendar. Every other person who got the meeting invitation still gets the reminders.
This is the only thread that I found somewhat relevant: http://www.eggheadcafe.com/software/aspnet/32118199/lost-functionality-when-accepting-meeting-requests.aspx
This is weird though because he doesn't have any rules that should cause the meeting invitations to be stored in a weird folder or anything, they are left alone. I tried loading his profile and accepting the invitation on my end, and it went through fine (it was marked down in the calendar with a 15 minute reminder). When I looked at previous meetings he accepted from that person, there is indeed no reminder set.
Windows XPSP3, Outlook 2007, Exchange 2k3