WD30EZRX can't be re-initialized

Today I received the 3TB Green and installed it in an old enclosure from an Elements. I initialized the drive but it only showed 2TB usable. I found out not all USB controllers support 3TB so I tried a newer enclosure (again from an Elements) and I saw the full 3TB in Disk Management. The problem is I can’t initialize the disk - Windows keeps telling me the media is write protected. If I install the drive in ANY other enclosure it’s recognized just fine, but I have only one that can see the full 3TB and it’s giving me problems.

I’ve used diskpart to clean the disc and check attributes (there’s no write protection) but I keep getting the same error whether the disk is formatted or not. I’ve also tried safe mode and uninstalling drivers. Is WD suddenly marrying USB boards to specific drives? I’m completely out of ideas here.

What Windows are you running? Windows XP only supports 2 TB drives top.