I'm praying someone can give me a miracle cure here but im pretty sure its a terminal case. i have a 24inch iMac 2.66ghz core 2 duo and a western digital 1tb external usb hard drive....this hard drive was bought a month or so ago with the sole purpose of store years and years of media to free up valuable space on my iMac hard drive....tonight without any warning at all the drive icon disappears from my desktop with an error message and now refuses to load, when i click initialise on the error dialogue box it takes me to disk utility. in disk utility i have tried repairing disk and i get the message "invalid node structure". it then tells me it cannot be repaired and i need to re-format my hard drive. as i said there is literally YEARS of info on this drive that i really really dont want to lose, is there anything i can do, or anything worth trying. as a side note on the front of the drive it has a capacity gauge and has gone from 3/4's full to not showing anything. PLEASE HELP!!!