If Microsoft worked on it for three weeks with no resolution, then you may
not have better luck in a peer support forum. Additionally, you haven't
indicated what you have tried already, so it's hard to figure out if anyone
here can provide further suggestions that won't repeat what you have already
tried.
That said, I would initially suggest re-installing Outlook / Office. Then if
that doesn't work, uninstall and re-install. Then if that doesn't work,
completely remove all components and re-install. Then if that doesn't work,
I'd consider whether I want to re-install the operating system clean with
Office, or try some different software. It could be that you have a conflict
with some other program installed, but there's no easy way to troubleshoot
that on a discussion board, so you may want to take it to a local PC support
place if the reinstallation / clean installation doesn't work.