Whs2011 Wakes Every Hour /lightsout

HI,

new to the WHS2011 and playing arround with LightsOut..works like a charm, except one thing.

The Server goes on when I start a Client and goes to sleep when the Clients are closed, only thing is, that the Server has lots of episodes where he wakes up and goes to sleep after 10 min for no real reason.

Settings are:

Backup or System Activity
WHS Computers
Remote ACcess
Console Session Remote Desktop Session

Wake on Pattern Match is off

MagicPacket is on

Going to sleep after inactivity of clients: 10 min

On the Network is also a FritzBox, a Canon Wlan Printer and Ipad..But they are set not to be monitored.

Any advice why nearly every hour the Whs2011 gets up for ten min?

Thanks,

H.