BTW I left no chance that any GURU Meditation errors occur, absolutely none, and I tested it, both with my memory card plugged in or out, but seems that a few people are still having problems. So if you are of those few, and you have a memory card plugged in your device, to be able to boot NITDroid, you should make sure that the file:
/etc/multiboot.d/11-NITDroid-mmcblk0p2-2.6.28.NIT.07.item
has ITEM_DEVICE in it set to {INT_CARD}p2
or else, NITDroid won't boot if there is a memory card plugged in.

I actually have a memory card plugged in my N900 at all times, and the installer just ran fine. One of the reasons that you're faing problems is because, maybe you are running the installer with no memory card plugged in, and then plugging in the mmc?