Hello and thanks for reaching out!
So sorry you are experiencing this issue! Have you tried a soft reset by pulling the battery out for about 2 minutes? Also make sure you have not added any recent applications/files that may be to blame. Try removing these apps/files and clearing the cache. If that does not work, try a factor/hard reset AFTER backing up your personal data first. Factory reset: http://bit.ly/KzplMQ
If you need additional assistance please contact us again. You can also reach out to us via twitter or facebook for quicker responses.
Thank you and have a great day!
Samsung Mobile Support is now available on Twitter & Facebook!
Chat Support: http://goo.gl/ZALJm