I got the same result, but was able to untar the backup file from a
terminal session. Say the file is backup.tar, then from the directory
it is in:

mkdir backup
chdir backup
tar -xvf ../backup.tar

This extracted a slew of *.tar.gz files which I was able to access from
a GUI file manager (Konqueror in my case).

bd
NSC Volunteer SysOp