email problem

When I try to open a link in my email this happens a box opens up and it says

Windows cannot find
Make sure you typed the name correctly, and the try again

this happens for everylink I try to open in my email I have Mozilla Firefox as my default but I changed it to IE and it did the same thing I have Vista Home. Eventhough the box comes up with the error it does eventually open up the link but I always get the error box first.
Thank You

Sylvia King