Process system is not responding?
Yes.
I too have an Archos 70 and had this same issue.
All I did was to turn it off, then reboot it in"Recovery Mode".


Turn off the device and wait 10 seconds.

Press and hold the volume + button while powering on the device.
Keep the volume + pressed until the Recovery mode starts (white screen).
To move from one option to another, use the volume buttons. To select an option, press the
ON/OFF button.
Then proceeded to run "Check Disk".



All returned to normal after the tablet was then rebooted.