I am sure that I used the right commands I read before when by mtkflash 1.80.1 without any commands.
But in the meantime my drive was no more recognised by the BIOS after trying another flash with hs0p.bin and the computer locked when detecting IDE-drives.
But I could solve the problem when I put the drive to another computer were it was not recognised too. But on this machine I could flash back to HS0K using mtkflash 1.80.1.
Now I burned a movie with my "repaired" LDW-811S without any problems in burning and playing the movie in the DVD-player!
So thanks for your fast reply.