Installation problems

[marget]

I recently got a macbook pro and i am running 10.8.2. Ive only had this for a week or two and everything has been going well until last night. I tried installing a PKG file for a cac card reader and it said installation has failed, contact the manufacturer and now every pkg file says the same message. Also i can not download anything from the app store from games to utilities. It gives me errors after "calculating the file" it says to goto the purchases page and then i go there and it gives me the same message. i even tried to update an app and it gave me the error, "cant update error 102" and i dont know what to do. i can download regular files from the internet