Can't open links in e-mails
 

Suddenly my computer is refusing to open links (eg to a youtube clip) that have been received in an e-mail.
The message reads "this operation has been cancelled due to restrictions in effect on this computer. Please contact your system administrator"

As this is a personal domestic PC there is no administrator but me, and I haven't touched anything, honest! I also have no idea how to fix it.

Baffled again.

Program auto updated causing the security settings to change?

Try looking in the options bit.

From Google:

Note: These solutions work in all versions of IE.
A very common question in the Microsoft public newsgroups goes something like this:
When clicking on a hyperlink in an e-mail, I get this Message : "This operation has been cancelled due to restrictions in effect on this computer. Please contact your system administrator." I get this message every time that I attempt to use the hyperlink. I am the administrator on this stand alone computer. How do I deactivate this feature so that I activate hyperlinks ?
This is not an Outlook error. The most common cause is a corrupt registry key in Internet Explorer. The registry key found at
HKEY_Local_Machine\Software\Classes\htmlfile\shell\open\comm and
is either damaged or corrupt.
To fix it, try resetting Web settings in Internet Explorer. If this does not resolve the issue, set IE as the default browser following the steps in Set Program Access in Control Panel. If you use a different browser as your default, you need to set IE as the default until you verify the links work in Outlook.
If you uninstalled Chrome (or Firefox) and then received the error, see Edit Registry, Part 2
In addition to Chrome and Firefox, other HTML rendering and editing programs may take the HTML open command and cause this error. Greg reports UltraEdit is one such program. See Edit Registry, Part 2 for the fix.

Default Web Browser
 

Good Evening,
This is not an uncommon problem it can occur when for instance one changes the default Web browser from I.E to something else say Firefox for instance.
Most of the time you can get around it by changing your system default Web Browser settings from the default settings tab on your computer but, this does not always work.
The best way is to Google a little program from Microsoft called 'Microsoft Fixit 50388' then save it to Desktop then run it, it will sort it in about a minute.
Hope this helps.