Links in Outlook: This operation has been canceled due to restrictions in effect on this computer. Please contact your system administrator.

If you get the following message when clicking links in Outlook:
"This operation has been canceled due to restrictions in effect on this computer. Please contact your system administrator."

This is caused by an incorrect or corrupted registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\htmlfile\shell\open\command

The key should read:

"C:\Program Files\Internet Explorer\IEXPLORE.EXE\" -nohome

Or in the case of Windows XP x64:

"C:\Program Files (x86)\Internet Explorer\IEXPLORE.EXE\" -nohome

Share Outlook Contacts Sub folders

In Outlook you can only share your main contacts folder by clicking on share my contacts.

To share sub folders, grant permissions on Mailbox at the root of the tree, grant permissions to your main contacts folder, then grant permissions to the appropriate sub folders.

On the client that needs to open the contacts, go to Tools->Email Accounts->View/Change, Ensure the Exchange account is highlighted and click Change. Click More Settings->Advanced Tab->Add, add the mailbox to be opened.

OK/Close your way out of the menus, click File->Open->Other User's Folder, find/enter the appropriate account, change folder to contacts.

You're all set!