Problem with Emonbase. Block every 1 or 2 days.

Hello all

I have a problem with my Emonbase. Every one or two days goes to block, and I can not solve. The red LED is lit, and emoncms not updated.
When he goes to block, if I scan the network with Look @ Lan, EmonBase not listed, and therefore it is assigned an IP.
It might be a conflict with the DHCP or other network devices?
How can I change its MAC address and assign a fixed IP to EmonBase?
The other modules seem to work,  Emontx and EmonGLCD continue to operate and detect temperature, consumption and production.
It could be a problem of power supply?
I'm using a USB Power Adapter 5V 400mA (Samsung battery charger).