Windows update problem

i am facing a problem from last three days,the problem is when i open my yahoo messenger,the msg i send to anybody or msg sent by anybody to me is not visible. i reinstall the yahoo,first old version then new 6.0 version but problem is still there.

Sec problem,when i want to update my windows xp from microsof,all site is accessible to me but when i reach at page that provide updates,i got blank page everytime.

third problem is my norton antivirus2003 crashed same day when these problem i surfaced.after removing and then reinstalling norton antivirus2003,one msg diplayed and when i click on ok on that msg,windows xp reboot itsself.now i uninstall norton antivirus 2003.