I have a problem booting from mmc. When I try to boot from mmc the Nokia logo appears and statusbar runs the whole lenght from left to right (before problems the bar run just to the level of A-letter on word Nokia and tablet started). After that the screen turns white and about half a minute later 770 boots itself back to bootmenu. I can boot from flash with no problems. Any ideas what can cause this and how to fix the problem (preferably without reflashing because I have a nice configuration of installed programs on the mmc bootable OS...)?

I am using OS2006 (both on internal flash and mmc, I like to boot from mmc to make 770 fast enough to run Canola), modified Craves SD card, SD kernel from Fanoush and I had also installed the WLAN memory corruption bug fix. The mmc seems to be working because I can access the data on it when I boot from internal flash.

The problem started when I tried to launch Navicore program (which I have used before without problems). This caused the tablet to crash to bootmenu and after that to continuous rebooting.

This sounds like corrupted system files if you don't have the wireless corruption fix. Run a fsck on the partition, write down the reported broken files by fsck and replace them after that. Then reboot and pray. Oh, and install the corruption fix. (I'm not quite sure if OS2006 was affected by the bug so maybe it got corrupted by other means).

Could you please give more spesific instructions on how to check the partition? Do I have to connect the tablet to PC or use a memory card reader or can I do it somehow from the tablet when I boot from flash? Thanks in advance!

I had the WLAN corruption fix installed.

I'm talking rubbish, you shouldn't mount it.

fsck /dev/[partition, usually mmcblk0p0 or something like that]

You can force a check with

fsck -f /dev/[partition]

Also read everything carefully

OK, seems like this has to be done as root.

I booted from internal flash and started Xterm.

First I typed: sudo gainroot.
Then: fsck /dev/mmcblk0p2

I get:
/dev/mmcblk0p2 contains a filesystem with errors, check forced.
Pass 1: Checking inodes, blocks and sizes.
Inode 15348, i_blocks is 16, should be 8. Fix<y>?

And now, because I actually don't understand what I am doing: to fix or not to fix?

EDIT: I selected "no" and went through the whole fsck procedure and got about 20 different errors (I answered "no" to all fix-questions). Other problems are of following types (there are a couple of cases of each of these errors, these are just examples):

Deleted inode 9422 has zero dtime.
Entry '32wd_to' in /var/lib/dsme/stats (94404) has deleted/unused inode
Unattached inode 94462
Inode 94540 ref count is 3, should be 2.
Block bitmap differences: -8505 -30734.......
Free blocks count wrong for group #6
Inode bitmap differences: -495...
Directories count wrong for group #0
Free inodes count wrong for group #6
Free inodes count wrong

Which of these errors might be relevant for the booting problem?

EDIT2:
I got adventurous and went through the fsck-procedure again. This time I answered "Yes" to all the fix and remove questions. Now booting from mmc works again!

Thank you Bundyo!

Maybe the 32wd_to one, but there are other not good ones like the wrong number of directories one. What is your file system btw?

FAT32.

I also had the following errors:
Entry '32wd_to' in /var/lib/dsme/stats (94404) has deleted/unused inode 92536. Clear<y>?
Entry 'ifstate' in /var/run (94540) has deleted/unused inode 91788
Entry 'dnsmasq.pid' in /var/run (94540) has deleted/unused inode 91794
Entry 'dbus' in /var/run (94540) has deleted/unused inode 495

So it was probably one of those that caused (see EDIT2 on my previous post) my troubles?

Yes, probably some processes tried to create pids in /var/run but they were broken. dbus is quite essential

FAT32 Interesting how you boot linux from it

Yes, you are right.

Partition mmcblk0p1 is FAT32 and partition mmcblk0p2 is VFAT. By the way, this was not the first time that I mixed these two.