I can't post messages to http://www.keil.com/forum/60400/ hence this new thread.
We did stress-test the file system quite a bit and are unable to see the problems you are reporting. Are you using the latest middleware releases? Can you provide us more information?
Note: this is not a support forum but a user forum.
In case that you have problems with our products, report the issue as described under http://www.keil.com/support.
A tricky part here is of course how the board is powered, and how the reset logic etc works.
The file system implementation may be perfect, but if the processor resets in the middle of writes, or if there are spikes on the SD signal wires, ground or supply voltage, lots of bad things can happen.
Best is an implementation with enough capacitors that the processor can detect the power loss and finalize any writing and return to a stable state before the capacitors runs dry.