Firefox failing file:// link protocol
Something I didn't know (before now) is that Firefox won't let you use the file:/// protocol link from within a web (i.e. http) environment. Or rather, anything linked to with file:/// won't open.
There is a local machine fix detailed here but it looks like for my intranet app I'm going to have to find another way to open files on the hard drive or network through the web browser.