Most of the times this happens after upgrading your
Outlook version. Rules are uploaded to your server. Local
rules and server rules can conflict with eachother. In
this case you have to choose between the server or local
rules. I always choose for the server rules as they will
also work when Outlook is closed (as they work on the
server). When you get this problem you should always
check your rules to see if they still do what you want
tem to do.
