I am having a weird problem with DiskEditor XP doesn't see the partition on my external Maxtor 300GB USB drive anymore. Originally it had: one NTFS partition no OS installed. I ran physical diagnostics on the disk, and everything checks out fine. No bad clusters or any other problems. I still can't see any partitions though, so I guess there is something wrong in the partition table in the MBR. I decided to give DiskEditor a shot at it. On startup, DiskEditor sees the disk as 279.5GB unallocated. I click on the disk icon so that I can edit the MBR for the disk. In the main window, I view the sectors 'as Hex' Absolute sector 0 The MBR is screwed up. So I load in the 512byte backup of the MBR that I made a few weeks ago when everything was working fine. It looks great. All the changed bytes are displayed in green. Offset 01be has the correct information for the first (and only) partition, the '55 AA' mark is at the end of the sector. I move away from sector 0 by clicking on sector 1. A message box pops up and asks: 'Warning! Sector 0 has been modified! Do you wish to save it?' I click yes, and then... everything gets shifted down by 16 bytes! bytes 0000 to 000F are now in position 0010 to 001F The rest of the bytes in the sector are shifted down too. The last 16 bytes 'wrap around' to the beginning of the sector, moving from 01F0 - 01FF to 0000 - 000F That's not the end of it. I click back in sector 0. Then I click back in sector 1. When I click in sector 1, the first 16 bytes from sector 1 are swapped with the first 16 bytes in sector 0! I click back in sector 0, they are swapped back around again. I can keep clicking sector 1, sector 0, sector 1, sector 0, and the first 16 bytes of these sectors keep swapping places. Are the bytes really being swapped, or is this a bug in how the app is displaying the sectors? I've just tried this with another random sector and the sector following it (on the same 300GB Maxtor drive), and the same swapping behaviour is happening there too. Ok, this is weird. So I tried to narrow down the problem: I tried DiskEditor on a 60GB external USB drive I had. This time no problems. No 16 bytes shifting or swapping on that drive. Everything worked fine. I thought there might be some malware on my machine messing things up, so I installed DiskEditor on a different laptop that had a clean install of XP with SP2, but had the same problems with the Maxtor drive. So something about the Maxtor drive and DiskEditor don't get along. Anyone seen anything like this before? And what could be causing it?