Check Canon's website, there me be a repair agent near by, if your tending toward the dust as the cause.
If not, see if you can get the firmware from Canon's website that runs the camera and put it on the SD card and run it. There may be a corrupted file in the camera.
If the camera is able to be updated there will be an entry in the menu for updating the Firmware. If there is and the Firmware doesn't appear on Canon's website, then either Google it, or email Canon to send you the EXE file.
As to replacements, is the G16 the latest version:
http://www.canon.com.au/en-AU/Person...al-Cameras/G16
It appears they skipped 13 and 14 and went to G15 then 16??
Good luck, it looks like a nice little camera. Would love to find a S/H one somewhere.
Trev