Help Mac iTunes/App store problem

Ever since yesterday whenever I go on to the iTunes store on my macbook pro it kept crashing.

However this morning when i click on the apps store or iTunes store a pop up comes up
saying "apple store/itunes quit unexpectedly while using the commericial kit plug in''. Neither application even opens, just that message pops up saying it has been sent to apple automatically.

Does anybody know what I can do or what I have done wrong?

 

I have noticed this is happening with most of my applications?
Oddddd