Hoping that *you* found this post via Google and this helps you:
If your Fantec QB-X8US3 enclosure keeps resetting and you get lots of sd or usb errors in dmesg, check your harddisks and *remove* flaky ones. I had random, frequent resets (unmounting all your drives forcefully…) when I thought I could use a dying drive as temporary storage in the enclosure. As soon as I removed that bad drive, the device was rock-stable again. 10++ would buy again.
Fantec QB-X8US3 is apparently the same as a H82-SU3S2 ProBox. Here’s a review.
Sincerely yours, DenverCoder9