why is out look express invading and taking over my hotmail account with no apperant couse to the effect ??

The question says it all.... i,m doing things on my good ol microsoft windows hotmail and out of no where , comes this yellow header at the top of my pg. telling me hotmail is shutting down or cant connect to hotmail right now try later, then the next thing i know, outlook express is on my screen along with  my hotmail life....this putter is on xp-2000 hm addi. i like my hotmail and i,m not a big fan of outlook express any help ???, thx ...