after I rooted my device with rupor's AMR it worked well for some days. After playing around (installing apps, etc.) it finally froze completely.
I tried both packages several times without any success. I was able to boot into recovery, SD light flashed for about half an hour, when it stopped I removed the SD and restarted. Now it always stops at 100% of "Opening book..." or the arrow-circle appears and then it freezes. Is there anything else I can try? (Except giving it back to the store and hope they just give me a new one without checking if it was rooted or not)
Thanks for all help!!!