If the screen goes blank but it's not rebooting on it's own or bluescreening, then it's likely a HDCP problem where the monitor you are connecting to (or application you are using) is causing the DRM to abort the HDMI connection.
I had this happen a lot, however since I've disabled HDCP I've not had a blackscreen since (*touch wood*)
You can find the HDCP option in the Adrenaline program (Settings > Display > Overrides and Disable HDCP)
I hope it helps.
