either reinstall drivers, or uninstall and re boot and clean reg cccleaner etc and re install or get the correct version of the drivers for the o/s your using, windows 8 64bit by any chance?
h88p://www.canon.co.uk/Support/Consumer_Products/products/Fax__Multifunctionals/InkJet/PIXMA_MG_series/PIXMA_MG5350.aspx?DLtcmuri=tcm:14-853623&page=1&type=download