Pictures are missing from camera

Probably your memory card is full, you should erase some pictures from the camera and it will work. It happened to my Canon G9 . I erased some old pictures from my memory card and the message Communication Error disappeared.

That did the trick for me! Thanks!

This G9 problem is really common. These cameras develop a problem with screws coming loose inside and causing a short in the camera. The place that a lot of people go for help with this problem is: www.camerasandparts.com They just work on the Canon Powershot cameras and nothing else and they do excellent work. The best part with them is that they do a correction inside the camera so the problem won't keep happening. They service the whole camera up and include the shipping going back, it comes to $89 with them. The work quality through them can't be touched, they are the place if you have a Canon. I hope that helps some. Good luck with the problem.

Your autofocus may need to be re calibrated-- this is not something you can do on your own, but it is something that could be done at a local camera repair shop. Take it in and see if they would be able to adjust it or give you an estimate.

The best way to download pictures from your camera to your computer involves removing the memory card from the camera and plugging it into a card reader (either built-in to the computer or connected via USB or FireWire). This is likely to be faster than connecting the camera to the computer, and won't run down your camera's batteries.

Once the card is plugged in, it will appear to your computer as a removable drive. You can use the operating system's drag&drop facility to copy pictures from the card to the computer's hard drive, the same way you copy any other files. Or you can use any photo cataloging program, such as Picasa ( http://picasa.google.com ).

the G3 was sort of a protype of thew G4, try tapping the camera lightly, not fixable, you can get a used g9 at great prices, or g10 ,g11

Call Canon Repair. It seems that you may have a ccd problem.
This problem may be fixed by Canon for free.
They have a trade-in or trade-up program also.
Call them at the following link: Canon Repair Support

No, you can't.
You only can transfer the pictures back to the camera if the pictures were taken by the same model cameras, plus the pictures were not modified.

A POSSIBLE SOLUTION:

i have the same camera but i want to use it like a webcam.
I found a driver that is located in the canon homepage, called "canon RAW codec"(compatible with Vista and XP), and it allows you to download the photos of the camera and to take fotos instantly, but it don't suport the webcam function...  :(  . I'm using it in windows XP.

That's all, Ithink that it must work for all the users.

Are you using the camera to upload the photos? I recommend that you get a SDHC reader(USB) and copy the files off of the SD card onto your harddrive. it is a common problem that RAW images cannot be read by windows or certain programs. Photoshop CS3 and later are able to read and open the RAW images from this camera if your "camera raw" portion of adobe is current. it is good practice anyway to load your photos directly from the SD card. I had a G9 since it first came out and now i have a G10--i have never even attempted to upload from the camera. don't let this discourage you from shooting RAW because it is the primary reason in my opinion for owning a G9 or G10. Let me know if this does not answer your problem...dj