I have the drive connected to the Mac Pro (Leopard 10.5.8), can start Time Machine and every time it breaks 4-6 GB from. Wrapped up and sent back. The next panel ordered - exactly the same problem. Only the time of abandonment is now earlier, at 0.5GB. Repacked and sent back. A third WD I will not try. The 500GB My Passport WD that I hang on my MacBook Pro (Leopard 10.5.8) is running without problems.
WD must have as a fundamental problem with the larger plates and Time Machine.
After I consulted with a few people, I got the tip to try a plate with Firewire connection. So I got me again a Western Digital. This time, the WD My Book Studio. About Firewire 800 runs the problems and extremely fast. So the USB connection seems to be the problem.