I just found this solution TODAY! After trying for a whole year to fix this thing... It was right at my face the whole time!!!!
1) Uninstall your old Canon MF5550 driver.
2) Reboot your computer
3) Download the Canon MF5550 driver Windows XP version.
4) Open your Vista Control Panel, then click on PROGRAMS (not on Uninstall or something else...)
5) bellow "Programs & Features", click on "use an older program with this version of Windows". Follow the wizard.
6) Locate the program manually. (If you need to search the folder where you downloaded your Canon driver, just go to search file on C. It will probably download on your desktop or Downloads)
7) Open the MF5550 Folder where you downloaded the driver, and click on the setup.exe file.
8) Choose on the next screen Windows XP
9) If you need to change the display settings, go ahead. But I didn't change anything. I just clicked NEXT.
10) Fill in the box: RUN THIS PROGRAM AS AN ADMINISTRATOR and click NEXT.
11) Click Next again and let Windows Vista do its job.
12) If it worked... just click yes and finish. If it didn't, click NO and run it again.
I AM SO HAPPY THIS THING WORKED!!!
Let me know if this worked for you!!!! I know I've looked everywhere for this solution...
email me at email@example.com
GOOD LUCK! GOD BLESS!