I've recently purchased an R4DS card (at least I think it's authentic), but the problem isn't with that. I've got a 2GB micro SD card onto which I'm trying to transfer the 1.18 firmware. It always gets to about 5 seconds left, and then freezes. I've left it like that for about 9 hours, but it still doesn't finish.
I've tried formatting the card numerous times, in both Fat and Fat32. I've tried installing the 1.17 firmware, but all to the same result.
If its an original R4 then it will support SD card NOT SDHC
Make does not generally matter at all, although I have found Kingston to be more problematic than most, I have used Sandisk and a range of non branded units all have worked fine
I've actually solved the problem by trying it with another computer. For some reason, on my laptop it won't transfer the firmware, but on the desktop, it will.