If you get the following message: "This operation has been cancelled due to restrictions in effect on this computer. Please contact your system administrator" while clicking links at any application (i.e MS Word, Excel etc.), this article might be helpful.
Possible reason: have you lately uninstalled Google Chrome browser ? Was that browser set as default ?
1. Install Firefox browser
2. Set the browser as default browser.
3. Via Control Panel -> Default Programs -> Set your default program
4. Select Internet Explorer -> Choose default for this program
5. Set all html related file types
Good luck !