I don't know if you ever figured this problem out, but I have had the same issue after building a new PC and using my previous RAID 0 drives. One drive (drive #2) worked fine, but the other drive was unable to initialize through Disk Management with the same DISKPART error you are having. I managed to fix this today, though.
Went to my bios and re-enabled RAID instead of ACHI. Rebooted and after the bios splash screen, a black screen appeared showing my drive information, then said at the bottom of the list press Crtl+I for RAID Configuration Management or something to that effect. Then a blue screen showed, listing my drives and 6 options. The first drive listed was the RAID 0 configuration at 931 GB (only a 500 GB drive). Option #2 was delete RAID Configuration. It then listed the RAID 0 config. Pressed DEL and selected YES to continue when prompted about loosing my data on the disk. Rebooted the computer, entered BIOS, change storage config from RAID back to ACHI. When the PC booted the drive had initialized itself.
Maybe this will work for you as well. I was at my wit's end trying to figure out the issue.