If taking the battery out and putting it back in fixes the issue, the problem may be related to either the battery (weak) or the contact terminals inside the camera, or a combination of both.
On my electronic and electrical equipment I fix such problems by cleaning the terminals and appropriately bending them if necessary. This depends on your expertise and level of comfort in performing such tasks.
Another option which I found effective is to check the Community forums. Others there may have had the same issues.
http://community.sony.com/?XID=M:header:esupport
Good luck!