My Canon Rebel has stopped importing pix properly, despite being quite new. It displays pictures ok, we get to Windows explorer to view them as thumbnails as normal(with 0 kb size!), which Windows cannot open or view, or drag or copy over. On the camera side I can zoom into the image on the LCD display. 2 memory cards and the same thing...

Try going to the Canon website for your country. It may be a driver problem in that the driver to download your photos is either out of date or incorrect for your camera. I had a very similar problem with my EOS 350D in that it would not import pictures from the camera to windows.
Occasionally my camera would take a photo of 0kbs but since my updated driver 6 months ago it has not done it once. Failing that get a 40D, the difference is amazing!!
Hope this helps.