Hi Thorsten, I uploaded "V4 .089_pre6_undo_disabled" and made some progress, (though I don't know if the OS made any difference.) I was able to get the sdcard recognized and got the "valid" response in MIOS, but with some strange behavior. I am only able to get the sequencer to recognize the sdcard immediately after uploading the OS to the LPC17xx. If I upload the OS with the card connected, then when the sequencer boots for the first time, it will find the card and load the necessary button/led/encoder settings. However, as soon as I turn off the sequencer, it fails to find the sdcard/load the frontpanel settings on every subsequent boot, and the only way I am able to get the seq to recognize the card/load the frontpanel settings is to reload the OS via MIOS. I have ordered another SD card and connector, as I'm hoping that perhaps It is just something card related. I uploaded a pic of my MIOS screen after uploading the OS, if there are other files or pics that would be helpful to you, please let me know. Thanks!