But now it no longer works. I started doing this right after 10.5 came out. I backed my MacBook (running 10.5) onto a hard drive inside my Sawtooth (running 10.4.11) with no problem for months and months after using the hack to backup to unsupported volumes. I recently moved around mid march, during the move I left my Sawtooth behind for a couple months so I was not using Time Machine to back up during that time period. When I finally moved the Sawtooth to my new house and attempted backing up once again I was getting error messages so I just deleted the old sparse image in hopes that if I just made a new one it would start working again. Now my MacBook is running 10.5.3 and every time I try to initiate a Time Machine backup it say that the disk image could not be created. At some point in time, with one of the 10.5.X releases did apple change the requirement to backup over the network to require another mac running 10.5? Or is there something else that is causing my problems? If they did in-fact change the requirement to 10.5 is there any way to get around it? I would put Leopard onto my Sawtooth but since it is only a 450Mhz G4 it is unsupported. Thanks for your help!