Hyperlink disappeared

We created a formula field that returned a string creating a hyperlink (ie. <a href=http://www.google.com>Google</a>) It was working beautifully until we logged in this morning? Now it is only displaying the text (no hyperlink)?

Previously it looked and worked like this: Google
NOW it looks like this (no link): <a href=http://www.google.com>Google</a>

How can we fix this?