My pixel size is 6956 by 2459 pixels and document size is 28.9 by 10.2 in inches. I cannot get it to print larger than 5+ inches in height. I am really confused now.
Dan
OK - you might be running into a limitation in PS CS3 under Windows. You have a limitation of around 10000 pixels. Because your image is 6956 at 240ppi it would seem fine, but the native matrix of the printer driver may be ressing that up when it's rasterised (the Epsons do this up to 360, for example) and then that data is "shown" back to PS and if it's more than its pixel limit under Windows it will have issues. I don't know if the Canon driver does this, though, so it's not a certainty.
With the Epsons, there's an option for "Coarse Rendering" which deals with this problem (output is still fine, just how it deals with the data) but I'm not sure about the Canons.
You might be able to try cutting it back to say 6300 pixels at 240ppi and see if that works (if so, then it's probably related to the above).
Other than that, I'm really not sure - I just don't know enough about the Canon driver. Someone else may have a better idea :-)