Try clearing cookies. As mentioned above some browsers will cache sessions with links. Not usually a problem until a company changes urls or links.

In FF 3.5.2 go to Tools, Clear Recent History. If your FF doesn't have this step, then update to this version.

In IE 8 go to Tools, Internet Options, General Tab, Browsing History, Delete, Delete.

If you don't have the most recent versions as shown above, you really should update as website generally start writing code for newer versions of browsers as they come out.