I suffered the same problem. This is how I solved:
The key is windows NEVER HAS TO SEE what will become a linux partition as a formatted one but as raw unpartitioned disk.
So first you have to erase you linux. You CAN'T avoid this.
Then, the order:
- ERASE THE linux partition (with fdisk or Disk Management). Remember, no partition at all on that 6GB (no linux format, no FAT format,....). Reboot windows several times until you can assure windows sees it as empty unpartitioned disk.
- Then reinstall linux.
The problem comes from windows "marking" the linux partition as "visible". If windows sees it as unpartitioned disk it will forget about it. If windows HAD a partition, it will think it is there for it's use although it's moved into a linux one. And it will not FORGET about it until you destroy it.
This works ok. It's confirmed from many other people.