I just received this in the mail today, and for some reason the loading screen during the start up doesn't seem to end. I'm using an 8 gig Micro SDHC. This is the R4 I bought if you want specifics: http://www.royaldsi.com/r4iiiupgrade-p/r4iiiupgrade.htm
Search for the correct firmware in the first website in my signature, or the second if there are problems. Usually the problem with the never ending loading screen is incorrect firmware, especially as there is like 14 R4s on the market. If NONE of the R4 firmwares work then you may have a clone, as there are maannny clones of R4s out there. Hope this helps!
Yes a bit mixed up!! ALL R4 cards apart from the original R4 Revolution are clones. They took the original and copied parts or all of it, most now are different as they accept SDHC cards but all are classed as clones (a copy!)