CAUTION: XO booting is sensitive to filesystem corruption

Been running rawhide-xo lately on my XOs. Have also installed q2e41.rom . Each XO has a "permanent" SD card. I was getting intermittent occasions when an XO would not boot -- soon after the screen background (as for "ok" prompt) changed from white to black, its boot process would hang with only a mysterious output message: " mount: unknown filesystem type 'jffs2' ". [If I repeated trying to boot, the hang would normally go away.] But today after I had used 'copy-nand' to replace 20090416.img on an XO with with 20090426.img, the hang (with that strange message) kept repeating. By juggling external USB devices [my usual "fix" for XO booting problems] I finally got that XO booted - but happened to run into a problem trying to delete some files from the SD card on that XO. Googled for help - and found that 'fsck' was suggested. Ran 'fsck' against the filesystem on the SD card [it found a number of bad references involving the files I was trying to delete]. And now that XO boots without hanging !!! My guess is that the problem with the (ext2) filesystem on the SD card somehow triggered whatever led to that strange output message which mentioned 'jffs2'. mikus