can you give some more info on 'buttons, infestations' etc. please? what version of windows does your friend have and what version of IE please? can you also tell us the manufacturer of the computer. may help a bit re: software that comes with the computer and how to restore it to factory settings if needed. try this maybe in the meantime:
to repair IE click here
ask your friend to download, update and run both adaware and spybot search and destroy click here click here these should help remove any spyware,adware or dialers that may have added buttons to the IE toolbar. remove anything they find,it wont do any harm.