navcancl.htm means Navigation Cancelled - without knowing which OS you are running or which version of IE I am only guessing as to the possible solution.
shdoclc.dll is Shell Document Object and Control library -
It is used by Internet Explorer to store localized items such as menus, dialog boxes, and strings. Using Multilingual Menus and Dialog Boxes for Internet Explorer can cause this error.
See if this applies:
Navigation is canceled when you browse to Web pages that are in different Internet Explorer security zones:
http://support.microsoft.com/kb/967941
After you install
security update 961260 (MS09-002) on a computer that is running Windows Vista or Windows Server 2008, you may experience a problem when you visit some Web pages that are in different Internet Explorer security zones.
This problem occurs if the navigation causes Protected Mode settings to change from On to Off.
This problem occurs because Internet Explorer 7 switches Protected Mode settings when certain Web pages are configured in the Trusted Sites area of the Security tab of the Internet Options dialog box. You can determine which Internet Explorer security zone a Web page is in by looking at the status bar at the bottom of the Internet Explorer 7 window.
By default, Protected Mode is set to Off for Web sites that are configured in the Trusted Sites area.
To resolve this problem, install the most current cumulative security update for Internet Explorer: http://support.microsoft.com/kb/963027/
I'm not sure what you mean by this or if it's part of the problem:
prior to a McAfee needed reboot
Please work through the update and see if it resolved the problem. I don't have enough information about your system to go any further at this point. This may just be a system problem caused by an update, so you need to try and resolve that first. You may have to move a Domain out of the Trusted Zone.
Nothing needs to be put in the Trusted Zone. This zone has lower security settings.
If the above doesn't resolve the error, please give me information about your operating system and browser, to include version. We will check for malware if it appears to be the cause or part of the problem.