Start with an uninstall/reinstall of the Office suite. If that does not work and this is a POP3 account then try running scanpst. If not a pop3 then try removing and re-adding your outlook profile. If this is on a domain try it on another computer and if it works then you know for sure this is a problem local to the other pc, which I suspect it is. You may need to have an admin rename your windows profile and then log in and migrate everything from the old profile into the new one as a last resort. But we really do need much more detail to give you accurate helpful information. Thanks.