I've found a sure-fire way to make my N900 crash using Easy-Debian. I'll look in greater detail if noone replies but thought I'd write about it first in case it's immediately obvious to someone else is what the problem is.

The thing I'm doing that's a bit unusual is that I'm mounting a LUKS-encrypted ext2 partition on my micro-SDHC card. This is important to me as I want to carry data with me that, for contractual reasons as well as common sense, needs to be encrypted. If I don't mount this partition then I don't get the crash. I haven't tried non-encrypted or other filesystems to see if that helps to isolate the problem.

OK, so on a freshly booted N900, running from a shell over ssh, I do the following to mount my partition:

$ cryptsetup luksOpen /dev/mmcblk1 mmc1
$ mount -t ext2 /dev/mapper/mmc1 /media/mmc1

then

$ debbie
Starting Debian shell...
Chroot dir specified: /.debian
No image file or partition specified.
ls: /media/mmc1/debian*.img*: No such file or directory
Mounting...
using image file: /home/user/MyDocs/debian-m5-v3d.img.ext2
fs type is ext2
Using ext2 file system
mounting /home/user/MyDocs/debian-m5-v3d.img.ext2 on the turbo-loop
.../home/user/MyDocs/debian-m5-v3d.img.ext2 mounted on loop1
.
..
...
....
Updating the /etc/mtab file...
Everything set up, running chroot...
[user@chroot: /]exit
exit

So far so good. Now I attempt to close the debian turbo-loop:

$ sudo closechroot
Closing the chroot...
...closing chroot apps...
Terminated

And my N900 bites the dust....... Any ideas?