New skin won't work with Firefox

[Stanley Steamer]

I made a new skin for a seperate password protected forum on my website.
I made the gradients with Gimp and loaded them to the host in the gradients file and installed everything on my site and it worked perfectly with IE.
But it doesn't work with fire fox, everything is black.
Is there any way to fix this?

[Mevo]

I made a new skin for a seperate password protected forum on my website.
I made the gradients with Gimp and loaded them to the host in the gradients file and installed everything on my site and it worked perfectly with IE.
But it doesn't work with fire fox, everything is black.
Is there any way to fix this?

First try to delete cookies ,If this not help ... Uninstall your Firefox than download new version of Firefox and install it.
Regards