07-02-2014 09:29 AM
It's probably been a while since you've restarted your phone and it has since collected lots of junk files.
While your phone is powered on, remove your battery then replace it a few seconds later. You won't lose any data and this will clear your phone's cache and will most likely resove your issue. You might even see your phone running smoother and quicker than before.
Let us know if that helps you.