ok v,7 kept crashing etc uninstalled it, trying to reinstall v 5 but can't find how to shut v 3.1 down to install v.5.

so uninstalled ver 7 cos was crap. then installed v.3 cos could not find vers 7, was then able to acces internet and yahoo told me to update vers5, so downloaded that now i can not find how to close it down to finish installation of vers 5. can't access internet or anything like mail.yahoo/and hotmail. help going mad..