Solution: Usually this is caused due to power saving mode. Centrino notebooks by default makes this function enabled in order to save battery consumption. The easiest way is to use the Intel PROSet application (if available).
Or through the properties on WI-Fi devices ethernet, on Network Connections. Then select Configure. In Adcanced tab, there are settings to optimize power consumption. Ad Hoc Transmit Power, influence the range. Meanwhile, Power Management, will adjust to the battery condition, and the idle time of the notebook. And will automatically reduce power consumption from the battery.
This, which may cause the Wi-Fi connection is lost. So there are two alternatives that can be done.
Option 1: Setting the maximum position for both of these functions. Especially if you're not worried about the remaining battery capacity. Because the available shortcut buttons to directly turn off the Wi-Fi in most Centrino notebooks.
Option 2: Customize the style of the use of your notebook. Learn notebook usage when idle. And tried in accordance with the habits of everyday use. Surely you do not want your Wi-Fi connection was suddenly interrupted by 5 minutes of idle time has passed. And you just leave your notebook, to simply going to the toilet or make a cup of hot coffee.