Problems with Outlook

I have Office XP and my Outlook suddenly is loading very slow. Once it is loaded everything work normally except when I try to send an email (this is slow too). I am using Microsoft Mail for the internal email. When I remove this account and leave the External email account active it work fine but as soon as I add the MS Mail account back it slows down.

Any suggestions? It was working fine before.

I have already tried reparing Office and uninstalling and reinstalling outlook with no luck.