The last post in this thread appears old so maybe these problems are no longer occurring for most, but here's a recent similar experience. I've a Nokia N800 with the 128 mbyte card that came with it and a 6 gig SanDisk microSDHC. I had flashed OS2008 to it and was enjoying it when suddenly both cards borked with the same symptom. Apparently read-only without the ability to set or clear the read-only flag. These cards could be written on another machine with a USB SD card reader.

Taking another post advice I backed up a the 6 gig card and reformatted it with the N800. After that it said it was corrupt. The offered repair did not fix it. A reformat did not work. I removed it to another computer and it appeared fine. I reformatted it and wrote a bunch of files to it but it again said it was corrupt in the N800.

I finally REFLASHED 0S2008 and now all seems well again, the cards are again readable. Hope this was an isolated incident.

..prollymolly