Ms Sharepoint And Mac Osx


I recently set up sharepoint on a server that will be used by a non-profit organization, and it seems like everyone on the planet can get access to it but me :-(

The service provider, Mail2Web, said that the problem resides in some security setting in my system, but I can't figure out what it could be. I have a wireless network with DSL. I have turned off the firewall at my machine, and checked about everything that I know how to but still cannot get access with my credentials, even though other people can.

Does anybody have an idea of what might be causing my problem?