Why Won't My Canon MP180 Scan a Document to My Computer?

My Canon MP180 printer won't scan a document and allow saving it to my computer. It will copy and print documents but when selecting scan document in MP Navigator, the error message 'scan failed' displays and nothing else happens. I have uninstalled driver and MP Navigator software (V3.03) downloaded from Canon's website but it still won't work. Canon's techs claim that my antivirus is blocking/corrupting the installation but that has never happened before. I'm running an HP desktop with i7 CPU, 8 GB of RAM and Windows 7 Pro 64 bit