I have only been able to gzip -d one file that ive downloaded so far.
i have redhat 9.0 and when i download mozilla firebird or fluxbox and try to tar zxvf or gzip -d, i get this error

gzip -d fluxbox.tar.gz

gzip: fluxbox.tar.gz: not in gzip format

or

tar zxvf fluxbox.tar.gz

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error exit delayed from previous errors

what do i need to do to decompress these files.
the only one ive been able to decompress was the tarball for VNC.
thanks

sometimes mozilla gunzips the file ... try using tar without the z ... tar -xvf filename