It could be over heating.
Make sure there is plenty of space round the case for cool air to get in and hot air to get out and disperse.
Sometimes dust and dirt get inside the case and block the fans and heat sinks so it runs hot. Some devices stop working when they get too hot.
If you are happy to do this, open the case and use a hair drier to blow out and dust and dirt (best do this outside).
If there is any stubborn dirt gently move it with a piece of wood (lollystick?) and then blow it out.
Brush off any dust and dirt on the fans with a CLEAN paint brush or other small brush.
Give it one last blow with the hair drier, put the cover back on, and connect it all up and try again.