Store makes me enter password numerous times, still doesn't connect, doesn't give me reason why.

I have been trying to connect to the store to access my account, buy new songs, and download old stuff that I have lost. Every time I try, I enter my password to which it responds saying 'accessing iTunes store' and then pops up with the window for me to enter my password again. That same thing happens several times before I get annoyed and stop trying. What is happening?

This is also only happening on my macbook (mid '09 model, 15"), which is what I use to sync my phone and iPod.