I have just received one of the new 512MB Pis. I followed the links to download and copy in a 384MB memory split file, replacing start.elf.
The Pi boots up fine, but when I enter startx it just hangs. Screen goes black, disconnects Putty session, and Pi has to be rebooted.
I tried with the mmc version of 384 MB memory split and the pre mmc version.
startx loads the GUI fine with old start.elf. I just can't access the extra 256MB of memory.
I was running with Turbo overclock, but have turned that off. Does not fix problem.
Does anyone have a solution? Can anyone suggest some diagnostics, or is it the board?