Usb host shield issues

How come after a few hours that the shield is on, it does not receive the correct data but only errors (type F0)?

Thank you!

F0 means receive timeout, i.e., device not sending anything while it should. What happens if you reconnect the device?

I will try tonight! In any case, it works correctly for a few hours, getting a constant stream of data without any error. Then he begins to work in this bad way.

Another problem: when I try to reset by pressing the button on the shield, in the new reboot, I do not receive any data. Only if I remove the external power supply (Vin, 9V), it starts to work properly. Do not use USB power, only external power supply.

I use the Arduino Ethernet shield + Official + SparkFun USB host shield, connected in this way: http://arduino.cc/forum/index.php/topic,51874.0.html

ok, I get again FO error (after more or less 2Hrs).

if I reconnect it, a first time
I get again continuous FO error, and a second time (after a few of seconds)
this error : "Setup packet error: E", and I don't receive
more data (even if the sketch continue to go). The usb
device don't has more the usb status active in his
display (instead it has when usb connection is ok).

then, if I press the reset button, the sketch starts again, but it can't recognize the usb device, so I have to switch off supply power and then switch on. so it starts to function again!

there is a way to simulate the switch off/on of the power supply?

in my sketch, usb polling starts with
"rcode = Usb.inTransfer( DEVADDR, 1, 8, buf, 1 ); "