I did a search of my computer's hard drive for test.dat. None found.
I have emailed iRiver about this, and they sent me the link you mentioned earlier:
http://nyaochi.sakura.ne.jp/iriverupdate/ But no instructions.
I called iRiver about this too, and the lady I spoke to was clueless about removing a European firmware and installing an American one. "Is it really that important?" she asked me.
I did a board search here about a week ago, but apparently I couldn't find anything, or the instructions I found were similar to the ones I located on the Internet.
I appreciate your help, but I've given up on this subject. I'll probably give this 1GB MP3 player to one of my relatives.