The Microsoft answers forum has a similar problem, solution being you need to enable Windows Image Acquisition (WIA) service.
- Open services. (Start -> Run -> services.msc OR right click on My Computer, select Manage, then select services.)
- Find Windows Image Acquisition (WIA)
- Set it to start automatically.
It may prompt you to also start other dependant services, e.g.:
- Remote Procedure Call (RPC)
- DCOM Server Process Launcher
- RPC Endpoint
- Mapper Shell Hardware Detection
One thing to note for further troubleshooting is that the WIA service runs as LocalSystem on Windows XP, but as LocalService on Windows Server 2003 and Vista (and Windows 7 I would presume), which might confuse confuse old drivers.
I've made a few comments above, but in the meantime check your Windows Firewall. Is Port 445 open?
EDIT:
Digging deeper into Canon's site, I've found the following:
Blocked Ports and Programs
In some cases, third-party security or firewall software may be blocking or restricting port traffic or programs causing unexpected results such as inability to install or loss of functionality. Check with the software manufacturer for information on unblocking ports or adding exceptions for specific programs.
The following are ports and programs necessary for your printer to function properly.
Ports
TCP 80
TCP / UDP 8611
TCP / UDP 8612
TCP / UDP 8613
UDP 3702 - (Windows 7 / Windows Vista)
The following port list applies only to models with memory card slots
TCP / UDP 137
TCP / UDP 138
TCP / UDP 139
Programs
IJ Network Tool
Default location
c:\Program Files (x86)\Canon\Canon IJ Network Tool\CNMNPUT.EXE (Windows)
/library/printers/canon/bjprinter/utilities/canon ij network tool.app (Macintosh OS X)
IJ Network Scan Utility
Default location
c:\Program Files (x86)\Canon\Canon IJ Network Scan Utilityl\CNMNSUT.EXE (Windows)
/library/printers/canon/bjprinter/utilities/canon ij network scan utility.app (Macintosh OS X)
IJ Network Scanner Selector
Default location
/library/printers/canon/ijscanner/utilities/canon ij network scanner selector2.app (Macintosh OS X)
MP Navigator EX
Default location
C:\Program Files\Canon\MP Navigator EX**\ mpnex**.exe (** refers to version number) - (Windows)
/application/canon utilities/mp navigator.app (Macintosh OS X)
Best Answer
If Windows sees the Canon, but doesn't connect to it, you might try a different piece of scanning software. Another fix is to try doing it from an admin account. I have had a very old 8400F, which Windows says is incompatible with Win7 and up, but it scans perfectly in compatibility mode. I also have two different Canon MP printer/scanners, and I've used them and the 8400F on one laptop, first with Vista, then with Win7, and on a newer laptop, first with Win7, then with Win8, now with Win8.1.
I found this question because I was looking to see if there was a new solution to the eternal Canon issue with its software: right at this moment, Photoshop and Photoshop Elements both scan just fine on the Win8.1 machine, as does Windows Fax and Scan as well as Omnipage 18, Arcsoft PhotoStudio, and SilverFast--but Canon's own MP Navigator suddenly doesn't "see" the scanner, although it did a week or two ago. It takes a long time to connect to the scanner, then tells me that the scanner is disconnected, that there's an "error" with the scanner driver, which is obviously absurd since all the other programs see it just fine. Reinstalling didn't fix it. It'll probably work again in a week or two, thank you Canon. (The problem is that I want to use the scangear driver, because it is more versatile than the scanning options you can get otherwise. To "adjust the quality of the scanned picture" from the basic scanning dialog box does not give enough options.) If I were you, I'd go to the device manager, then imaging devices, and see if Windows thinks that they are all working properly. One trick that sometimes works is to disable the device, then re-enable it.
I've had a nightmare ever since getting my first Canon on 1/4/06 (the 8400F), and then the MP printer/scanners a few years ago. The physical aspect of their products is excellent: the problems are the drivers and the software. I've had to uninstall/reinstall both their drivers and the Canon programs literally dozens of times over the years. With the old Windows 7 laptop, I eventually had to do all my scanning from an admin account, thank you Canon. That did minimize the number of uninstall/reinstalls necessary.
I would uninstall all the Canon software and drivers, preferably using Revo to make sure all the miscellaneous files and folders are deleted; make sure that you reboot when you're through, then reinstall everything from an admin account, and reboot then also (this is for any Windows from Vista on.)
Before doing that, you ought to run sfc /scannow (you have to use an elevated command prompt), just for the heck of it, and there's no law against running scandisk regularly either, although, on a non-SSD machine, it takes an eternity. If nothing still works, I'd go to Microsoft's site and run any relevant automatic fixes. If that doesn't work, well, there do exist other scanner manufacturers.