Thanks for using our forums. Sorry to hear you are having an issue keeping power to your Slingbox. If you have checked the power adapter and it is putting out the correct amount of volts, it may be that the Slingbox itself is faultly. Please contact us with the serial number of your Slingbox and brand of power adapter and we should be able to help you further.
Hope this helps,
The Sling Moderation Team