First off you didn't mention your OS,XP, VISTA, Win 7. If the unit came with CD/driver disk , assume you loaded. Depending upon the OS, it sounds as if it could be a compatibility issue (software). It may be that you need to update the drivers (if available) from Canon's website. Having seen this many times with many and most manufacturers, it may be resolvable. There are occasions, however, when the unit to OS software upgrade is not available. Best of luck.