Hello everyone. I recently bought a 4TB hard drive to be used as an external backup hard drive and was indeed faced with the dreaded 2TB limit of Windows XP. This is what brought me to purchase a copy of Paragon GPT loader. Except that things weren't happening like they should. If tl;dr, directly go to the end of this post for the solution On first I created a whole 4TP GPT partition under a Windows 7 install and started to copy some files. On my main install (Windows XP SP3), without GPT loader, Windows would insist on trying to read the GPT partition even if it is natively not supposed to do so! The partition was visible in disk management and I could even assign a letter which was odd. But there were some weird limitations (partition still missing from "My computer", file and folder names being limited to 8 characters long, forced to reassign a letter after reboot, etc.). My problems remained after installing GPT loader, and GPT manager would even label my partition as "Unknown". Also, the most important: Disk management still insisted to interpret my GPT partition as MBR for an unknown reason and GPT manager was totally incapable of detecting any GPT partition. Then I did a fresh install of Windows XP on a spare hard drive and connected my 4TB to it. Things were happening as they should with Disk management labelling my partition as "GPT protective partition" as intened. After installing GPT loader, everything was working like a charm! From that, I wiped my 4TB and created 2 2TB GPT partitions, to make a fresh start. Back on my main install, with GPT loader installed, both partitions were visible under Disk management but same problems as above. With GPT loader uninstalled, only one partition was visible with, again, the possibility to mount it... From that point, I hunted high and low in order to track the culprit, as nothing similar could be found on the internet, not even that forum. I guessed that my case was rather uncommon and very rare. Then I cloned my main install to another spare hard drive and started to remove some services from the registry... until I finally found the culprit! For some reason, AppleHFS was installed on my main install without remembering when. Immediately after putting disabling the AppleHFS and AppleMNT services, everything worked as intended! So, to sum up, if you have AppleHFS installed on your computer, please get rid of it, as it can't cohabit properly with Paragon GPT loader! Here's how to do so: - Open Windows registry by typing "regedit" into the Run dialog (Win+R) and click OK - Go to HKEY_LOCAL_MACHINE -> SYSTEM -> Select and remember the number you see at the "Current" value (let's call it "x") - Then go HKEY_LOCAL_MACHINE -> SYSTEM -> ControlSet00x -> Services -> AppleHFS - Write "4" at the "Start" value, this will set the service as "never run" - Then go HKEY_LOCAL_MACHINE -> SYSTEM -> ControlSet00x -> Services -> AppleMNT - Write "4" at the "Start" value and reboot your PC On next start, your Disk management should recognize any GPT partition as Protective GPT partition instead of tryiing to interpret it as MBR. And installing Paragon GPT loader will actually recognize your GPT partitions properly and give you the possibility to use your whole drive. Please note that AppleHFS is made by Apple and has nothing to do with Paragon's own HFS driver. Even if my case is rather uncommon and weirdy, I hope this can be helpful for the next people encountering the same symptoms. Further info: The 4TB drive is connected through a jMicron eSATA connector and the JMicron controller is set to IDE mode within the setup. Please note that you have to use the original Windows drivers for the drive to appear and not the JMicron one (otherwise drive detected as SCSI and therefore unusable). Indeed, you will say bye-bye to hotplug and have to refresh your devices in the Device manager each time you connect and disconnect the drive.