Why does my mac date everything 9/10/2010? every email, every message, everything, Why does my mac date everything 9/10/2010? every email, every message, everything

My Macbook Pro dates everything 9/10/2010. Besides items that happen today or yesterday, everything has the same date whether it happened last week last month or last year, it all says 9/10/2010. This happens with everything; messages, mail, etc. This is very annoying when trying to remember when something happened or when trying to find an email that happened on a certain date. Can anyone please help? Thank you...