Just disconnect the printer, restart the system & connect the printer again!
It should detect the printer automatically, if asked for drivers, browse the explorer & provide the location where the printer drivers are downloaded OR Double click the driver (.exe)file!
Download the correct drivers for Windows 7provided at here (32/64 bit), also with Toolbox Software & firmware update tool! Install them all & tryhttp://www.usa.canon.com/consumer/controller?act=ModelInfoAct&fcategoryid=124&modelid=14444#DownloadDetailAct
(Sometimes 32/64 bit drivers also cause some problems, if installed in wrong version)
Before installing latest drivers, follow the good habit of removing older driver versions using
Driver Cleaner Pro 1.5 (Freeware)http://www.afterdawn.com/software/desktop_software/other_tools/driver_cleaner_pro.cfm
These tools may help you to remove the traces left!