iTunes

is anyone had trouble getting iTunes to load it goes all the way through the setup then tells me it encountered a problem i cant open it.  ive tried every route to get it to load ive used a two different disks with virus protection on then w/o then i downloaded it stilll doesnt work then i completely erased every thing that has to do with it and it loaded fine it restarted my computer and when i signed on it was gone. please help i need this to load