Itunes closes directly after opening

I've been using my itunes with no problems, then this morning I turn on my MBP, open itunes, and then all of a sudden it closes after literally 2 seconds, and the box appears 'the application itunes has quit unexpectedly'

this happens over and over, how can this be fixed?

I also have the latest version, i believe its 7.7

update: now it doesn't have a disclaimer box after it closes, just opens and closes in a split second