However, when i insert this one into the phatbox, i get the blinking green light. I believe this is a boot-failure.
Can you describe the pattern and speed of the blinks?
When i insert the disk in the cradle again, the PC get's irresponsive.
The disk does not seem to be recognized anymore. When i re-format the disk as FAT, no issues at all... Hardware seems fine. ?.
What Windows version (and architecture) are you using? I had a similar issue with a WD1200BEVE drive in a USB 2.0 cradle on Windows 7 x64.