update on my own post.
Do not try to update the firmware in an attempt to get things right. I just did, and got a microsoft windows system update screen. it cannot find anything, and after two attempts, my 1 week old Archos 20c was DEAD !!
When I plug in the USB cable, nothing appears in windows any more. I cannot switch the Archos on any more either.
update again. it isn't dead. i pressed the 'on'button really long, and it starts up. Still completely empty. windows says it is a working device, but cannot access it, and it cannot format it either.
Archos says you should use diskmgmt.msc in windows, and reformat MBR scheme/FAT32. The Microsoft help page on diskmgmt ( http://support.microsoft.com/kb/308424/EN-US
) is incredibly dumb, ,it just describes all the options you would find yourself when clicking in the disk management window. It may solve your problem, but be careful. After doing it, i could open the device, after making four directories however, Windows got stuck when I tried the fifth, all the directories that I had made, disappeared, and now Windows does not recognize the USB device at all any more.