my camera had the same problem i reset factory defalt by holding down the menu button for 10 seconds then reset its back to normal now ,im not saying it will work for you but what ya got to loose
cannon Pro1 Default Settings
On the Canon PowerShot G5 and Pro1 cameras, you can easily restore the factory default settings by pressing the Menu button on the back of the camera for 5 seconds or longer.
When you get the "Reset settings to default?" prompt, use the right arrow on the Omni Selector button to select OK. Then press the Set button to restore the default settings. Now all you need to do is change the resolution and compression settings. On the PowerShot G5 and Pro1, go into camera mode for taking pictures, and then set the resolution by pressing the FUNC button.
Use the Omni Selector to scroll down to the bottom entry in the list for resolution. Then press the right or left arrows on the Omni Selector dial to move between and select one of the four or five settings:
M2 or M3 for 1024 x 768 (recommended)
And press the FUNC button again to save the setting.
Next set the compression by again pressing the FUNC button.
Use the Omni Selector to scroll down to the second entry from the bottom in the list for compression.
Then press the right or left arrows on the Omni Selector dial to move between and select one of the three settings:
The middle setting (Fine), which is recommended
And press the FUNC button again to save the setting.
Finally, turn the Mode dial on the top of the camera until the word AUTO (in green) lines up with the black line to the left of the dial.
Now if you want, you can personalize the menu settings or switch to a manual mode of shooting.
beezmaster
June 2008