i need help!

I took some pictures with my canon powershot SD100 but some of the pictures would not open when i uploaded them to the computer because they are in. ctg format instead of the usual jpg. my question is does anybody know what a .ctg file is? and how to open them? :confused:

From what I can see on the www .ctg files aren't pictures.
I think they are control files for the camera.

http://www.webopedia.com/quick_ref/fileextensionsc.asp