I use Windows XP Home Edition SP2, MS Office Outlook 2003 SP2 all JP version

I am the administrator of my PC. In it I have created an event (schedule)
in Outlook with a URL link. When I open that event and click on the said
URL, my browser (Firefox) does not open, but instead I get the following
message (translated from Japanese): "Due to restriction set on this
computer, this operation has been cancelled. Please contact your system
administrator."

Can someone tell me how I can access the brower by clicking on the URL
inside Outlook event?