I admin another place and have a little experience.
Thing is, it's dependent on your particular forum software, access and setup and andrewas has a good point, it does sound like server level issues. Might need to check with the software people and the server. If changes were made to the server (such as security) it could affect the ability to post or email notifications.
I'd suggest checking with the server people first.
[ 08-02-2006, 01:39 PM: Message edited by: Cloudbringer ]