Probs With Yahoo Messenger(malware?)

its me again but this time i didnt do anything
my yahoo messenger is misbehaving o!, when it starts er'thing is okay till you type in your id nd password then the thing closes, thats right it closes jst like that, i've tried uninstalling it and redownloading the prog but the prob persisted, i tried to use system restore but it refuses to restore to ANY of the previous restore points!!!, any bright ideas? i'm really opwn too suggestions(using trillian now but people that use it can testify;they have the worst emoticons)

i'm running XP home sp1 on a P4 2.8Ghz 512mb 40GB tosh satellite