Minecraft not letting me log in?

Friend payed for it but I can't log in at all even with right info… I go to her house with the same laptop that doesn't let me log in, and magically I can now log in (but only to the site, not the game itself…) help anyone?

in case anyone asks I did verify email

A couple of months ago minecraft changed its login protocol. Just keep going through the "forgot my password" "forgot my account name" "update my username/account" things until it works. It took me a while.

also make sure that the same information is used on:
minecraft.net
mojang.com
and your actual minecraft.exe login.

you should also re-download a clean minecraft install just to make sure there isn't any old log in data stored somewhere thats messing up your ability to log in.