Mac Will Not Find My External Hard Drive - Time Machine Question

ok, it's been hooked up doing fine for a week? or so. today, it will not backup, the puter can't find the backup disk.

rebooted everything, no luck

any suggestions?

once again, it was user error...the firewire adapter had came out

nice to know y'all are here though!

Wish my current was a PEBKAC - Ext HD which was mounting with FW800 for last few weeks will no longer show up. Tried many combinations of leads and sockets but have been reduced to FW400 until i find the cause of non appearance. This on the 24 - mounts OK with FW800 on the 20