At first: sorry for not answering questions and stopping developement. More explanations later in the post...
@qlob: According to the crashlog (line 238 in code) it should be an error with the launch of /mnt/us/system/mplayer at the kindlets start (it starts "sleeping" and waits for tasks). Try killing the mplayer process manually, restarting the kindlet and at last maybe swap the mplayer binary. Yes, this comes far too late, sorry...
@jmesar: I didn't see how the landscape mode could be useful for this app so I removed it in the textoption menu. I actually forgot the possibility to enter landscape mode outside the kindlet. And I don't know if KindleDX can handle this, I thought it should. But according to your experience it doesn't seem to...
And for the older post: Yes, you need writing permissions to edit the file, but I'm not sure, if the last line ("mntroot ro") is needed.
And now to everyone else:
In the last time, many things have changed. I had my kindle sleeping in it's case for a long time (lost interest/was busy) when I decided to read some interesting articles in the web ca. one month ago. After reading and returning to home screen I saw a new "book" in my list called "Test Kindle Installation Result", by "Amazon". The content of it was a message about the fact, that my kindle was no longer a testkindle with the ability to play unveryfied .azw2 stuff. To proof this I tried to open an app, but the same message popped up, that you get if the device's developer.keystore isn't the same as the one your app is signed with. Of course the next step was having a look into "/var/local/java/keystore/" and voila, the whole content changed. There's no longer a developer.keystore, but instead "developer-application.keystore" and "application.keystore" (the new content of the folder "/var/local/java/keystore/" and the message in .azw format are attached to this post, both in .rar-archives becouse of mobilereads format restrictions).
Obviously "developer-application.keystore" uses another decryption than before and as long as I'm a noob at this stuff, I gave up the whole thing after some desperate tests. Sadly I don't have a backup of my kindles filesystem to return to an earlyer state, I don't think this is the only thing that they've changed (don't know why this wasn't the first action I performed with my kindle when I got it...).
Of course it's my fault, becouse Amazon is allowed to change files on my kindle when I'm connected to the web via wifi and if I did unauthorized things, as long as I agreed with their terms of service... But to be honest, I didn't expect them to become active ^^
I could have asked mobileread for help but however I am fed up with Amazon at the moment and in addition to that I saw the benefits of a touchscreen at my friends eBook-readers, so I decided to "upgrade".
I sold my Kindle 3 and am going to buy a Sony PRS-T1 now, becouse of touchscreen, Android (huge software amount), NOT-Amazon, weight/size, etc...
Sorry for my betrayal
For you this doesn't mean so much, as long as I have been extremely slow with useful updates the last time...
Regards
Kuja