I think I have messed up things here.While downloading all sorts of codecs and converters I began to get 'explorer.exe has generated errors' while trying to open video files with in a folder like My Documents or New Folders created by me.I uninstalled many things and did everything Microsoft Support recommended but it just did not go away.Finally I uninstalled the Widows media player.While doing so,I think I corrupted or damaged or deleted some operating system file.Suddenly from the music or video file icons,the symbols of the default player disappeared and all are in the window icon mode.I can still play all of them through VLC player,Quick time alternative etc but I have to chooses them.Also when I double click a music file the message comes 'Widows cannot find Program.exe.This is necessary for opening files of type MP3 files"How to fix all of these problems?Have I to reinstall the entire operating system.If so can I switch to wxp and IE7