I think it's the new firmware. This didn't happen with the SDHC kernel patch.

Bug 1024 started before v4.2007. And I had already Problems with one
of my SD cards in first N800 firmware 2.2007!
I am not sure if this problem is really caused by the kernel.
Perhaps some background daemon (like metalayer-crawler) is the problem.
But I think that this problem became larger with the new firmware.

So the latest on my front is that the problem was repeatable using the Transcend 8Gb SDHC card in either the internal or external slots.

I'm fairly certain it wasn't Canola reading the files, rather that when writing the files it all went screwy.

After 3 or 4 of these FAT corruptions, Windoze then started reporting the card as actually being 6.84Gb (down from 7.5Gb formatted).

Another couple of tests (hey if the card is toast why not?) and it is firmly past it with no piece of software I have access to being able to format it at all. Windoze is reporting multiple disk errors and it all looks terminal for the card.

A chat with Transcend last night and they recommend returning to retailer for help.

For now I am rolling back to V3 with the patch before going anywhere near SDHC cards - at least until a patched kernel is released.

I have a 2GB Kingston MMC Card in the External Slot. It works fine with the v3 firmware, but as soon as I upgrade to v4 it appears as corrupt. If I reflash back to v3, the card is detected and I can read/write to it just fine. The same card can also be read/write from my 770, my Nokia E60 phone and a Windows XP PC. It just seems to be the v4 firmware that can't mount it in the External Slot. I don't think it works in the Internal Slot with the v4 firmware either, but I have rechecked it since going back to the v3 firmware. It's not specific to one particular 2GB card either; I have a second one in the 770 and that behaves in exactly the same way.

I had this behavior with v3.2007 (Transcend 8GB in external slot) and sdhc-kernel!
Some input/output errors while writing to SDHC and then only 5GB were
recognized! My dealer exchanged this card.
What I didn't knew was that "Panasonic SD Formatter" can reformat these
cards and recognize the "real" size... It could be possible that this tool
is able to revive such a card!
But my newly corrupted cards aren't recognized by this panasonic tool anymore ;(

My Class 6 8GB Transcend SDHC card has just gone read only on me using the v4.2007 kernel. This happened before using the v3.2007 with SDHC patch. I don't run canola, but make heavy usage of media player and mplayer. I use gpodder alot for downloading podcasts but the files are written to my 2GB RS-MMC card which has never had any problems.
Last time it was fixed by a reformat so will try that again.

i ran the sdhc patched kernel on my n800 without any issues. when i put the new firmware v4 on my n800, the card was giving me read only errors and what not. i thought it was data corruption and reformatted the card.

after the format, and loosing tons of maemo mapper tiles, i could then write to the card, but only for a short period of time. it soon was back to read only access even though a 'mount' from the command line showed the mount point as 'rw' (read/write enabled).

again, i had no issues with fanoush's sdhc kernel patch on v3 firmware, but more and more people seem to be having issues with the v4 firmwares sdhc support. i would hope that if my card is ruined, that i would be entitled to a replacement. i have to do some triage to see if the card is writeable in other devices (windows laptop, linux server, etc), since my n800 now does not even see the card when inserted.

does anyone know if a surface scan on flash media will turn up bad sectors in the media, even though there really is no physical media?