As you're all probably aware, the argv-restart code is a little dodgy at best (thanks to using the C stdlib on Windows, mostly), and munges the parameters into short paths because no-one could be bothered quoting. So starting Firefox locally, Windows launches with this command-line: "C:\Program Files (x86)\Deer Park 2\firefox.exe" After the restart, it is: C:\PROGRA~2\DEERPA~2\firefox.exe This is horribly ugly, but it works. Now, if you start it from a network share, this doesn't happen (I've not looked at the code, so don't know if it simply ignores network paths, or just calls the wrong APIs). So Windows starts with: "\\gold\Firefox (trunk)\firefox.exe" After the restart, it is: \\gold\Firefox (trunk)\firefox.exe Which naturally does not work right. The Win32 API involved (ShellExecute, I expect, under all the C stdlib wrapping) can handle this (so Firefox does start), but Firefox itself really doesn't. It tries to open the page "file://///gold/Firefox%20(trunk)/(trunk)/firefox.exe". Personally, I think the arguments should just be quoted if they contain a space. It's a really simple bit of logic, and will work in both situations (not to mention wont look ugly as hell). Anyway, it needs fixing. :)

This was fixed by bug 303599. Wooyay.