In fact, the U36 IC is the current limit power switch. It provides power to the USB device attached to the USB Host port. It is designed to provide an output current of 500mA. You shouldn't connect USB devices that require more than 500mA.
On the other hand, this current limit can be less than the full specified depending on the temperature. You pointed that your system worked for 4 hours, did you notice any increase in the temperature during that period? That might be a possible cause of the issue.
What is the USB dongle you are using? We can check its current requirements to learn if that could be another possible cause of the issue. Anyhow, if you consider that all your system and hardware settings were fine, you might want to submit a ticket filling in this form: Intel Support. You will receive a deeper support about this issue.
thank you for the answer.
The first system worked for 4 hours, but I didn't notice that the temperature increased.
The USB dongle I used is included in to the laser pointer. This is the model: http://www.augustint.com/download/manuals/LP170_EN.pdf
Moreover, this laser pointer was tested yet with Intel Edison, so I don't understand why it should draw more than 500mA.
I think that I'll open a ticket with the Support.