For no unknown reason sometimes my internet and the DSL light goes out this happens when a webpage takes time to load,and after about a minute it connects again.I have noticed even when the computer is off the internet light as gone out and then connects.
U might want to think about getting a new power cable. This had happened to me some time back, at first i thought that it might have been an internal overheating issue with the modem, but changing the cable helped. Good luck.