Email links in Outlook not working

Hi All. Pretty desperate here. One day I tried to click on a link in an email I received in order to get more info, as I always do...and got an error message from MS Outlook reading: "This operation has been cancelled due to restrictions in effect on this computer. Please contact your systems administrator." As far as I know I did nothing different (I probably wouldn't know how!!) to make this change happen. I've always clicked on links when I get emails with info etc. Always. I can't figure out what happened. I'm running Outlook 2007 and IE 8 I believe, and Vista.

I've tried going into the internet options and ensuring IE is my default browser etc, as suggested to me by someone else, and that has never changed. Really confused and frustrated.

Any ideas?? I'd be forever grateful
Chere