Thank you for your reply
There is another strange behavior I noticed just now using the SDFat library. If I run the benchmark sample it failes to write on the SDCard but it still creates the file. Corrupted of course. While the sample that displays the information about the card work without an error.
There is a possibility that this is a card issue, but I have 16MB and 128MB cards that arent working at all.
I formatted the card several times using the offical software drom SD website.
Can you post a sample of code using the SDFat that works for you? So I can try to run it and see the results.
One more thing I read something about the length of the cables between sdCard module and arduino. Mine are quite long about 10cm, could that be the problem maybe?