TIme Machine won't back-up, crashes OS, can't repair external hard drive

I am using Leopard with an ibook G4. I have a western drive passport elite, 320 gb. I was able to use time machine once. I tried to update it recently and left if over night. The next morning, my computer was off. OS has "quit unexpectedly". My external drive no longer appeared in the finder. I used disc utility and tried to verify and fix disc. It was unable to do this, I can't remember the exact error, something to do with siblings. I had to erase it and start again. It appeared in finder, I started time machine, and same thing happened. This is obviously a little frustrating since I have to erase the external hard drive in order to read it again. Sort of defeats the purpose of a back-up. In desperation I am just copying everything over without time machine's help. Has anyone experienced this? I am not very impressed with TM right now!