system
7
dear diomar,
you are not alone 
i have the exact same issue with xp sp3 / outlook 2003. the avast outlook plug in crashes outlook
at every start. this prob. first came up with 5.1.889 and persists ever since. only solution so far
is to uncheck “incoming/outgoing messages” in the avast email shield
i submitted a support ticket but the answer was a standard “… we are looking into it …blabla” message
so i don’t think that there will be a fix soon.