my newly updated itunes will not open

To Whom this may concern,

I have a 15" mac book pro laptop, running snow leopard operating system. I updated my Itunes account about 2 days ago when my security updated popped up, and now i cannot open my itunes. When I click on the itunes icon to open it, it pops up this box that has no writing, however it has a button to press ok, and my itunes will not open. I have tried restarting my computer, i have tried turning off my computer. Please Help!