|You could uninstall Acrobat Reader from "Control Panel > Programs and Features". then re-install it.|
At this point though, I am unsure whether you should install Acrobat 5 from the Canon LIDE CD or use the latest which is Acrobat 11. It is possible (but not certain) that Acrobat updated and this caused the trouble.
Always pop back and let us know the outcome - thanks