Sorry to hear of your problems. I have successfully installed 8.6 on my 6100 w/ a Newertech G3 upgrade card. I don't know if this will help, but I hope so: I upgraded a minimal 8.5 folder on a zip disk to 8.6. I then started up from the zip disk. From there, I ran the 8.6 update on my hard-drive's System Folder, restarted and everything is fine.