IOHDIXController Error (Acer 3810tg)

I wanted to use my spare time in this holidays to install Snow Leopard on an external drive for my Notebook but got the following error:

To sum it up:

hdik: attach failed: error 0000006b
Creating RAM Disk for /var/tmp
IOHDIXController::createDriveInKernel: returning error 0x6b
  ...
(repeats with another 2nd line a few times)
  ...
using 64-bit bootcache playlist
launch_msg(): Socket is not connected
launch_msg(): Socket is not connected

My system:
Acer Timeline 3810tg
Windows 7
Bios: v 1.10
External 100GB 2,5" HD
SL-DVD

What I did:
1) followed the lifehackers-guide ↗
2) got a Kernel-Panic -> followed the instruction of some posts and deleted the "dsdt.aml" on my USB-thumbdrive
3) installed Snow Leopard on my external HD
4) restart
5) error above

I would be glad if someone could help me with this error. I really want to have my OSX
Greetz

ps: already googled a lot and tried insanelymac and this forum without success