Disabled Hyperlinks in Emails?

I believe Norton (or perhaps Windows or Outlook or IE?) has disabled any hyperlinks that I have in emails. This is very frustrating. I only click on hyperlinks of known locations which I receive from trusted sources. There are workarounds, but they're a bit of a bother.

 

Does anyone know what causes this message when clicking on an embedded hyperlink in an email message and how to remedy it? FWIW, I'm running Windows 7 64 bit, MS Office 2007, IE 8 and Norton 360 4.2.0.12.6241i6CBD3BDED558E875