When i woke up this morning i found my icons and my start menu not appearing so i looked online on my phone for what caused this and i found out it was the microsoft security essentials...sooo..seeing as how you cant delete essentials when in normal mode because it is being used as a process...I myself started up my computer in safeMode which only ran the bare essentials for windows xp..i then went to add/remove programs and deleted Microsoft security essentials... If you would rather keep the essentials on there is a way to disable it in safe mode....I went to my control panel/Administrative tools/Services. once your there find Microsoft security essentials antivrus (it will be something of that nature, i dont remember full name) right click it and go to properties and there should be a dropdown box...Choose disable...restart your computer in normal mode and everything should be working just like before....... I think microsoft is forcing people to upgrade by screwing with everyones systems who run XP. They knew this would happen