Monitor goes to sleep

Just bought an HP 2009v monitor and it just went into sleep mode with screen message 'monitor going to sleep'. All connections are OK. Tried to turn off the PC but it wouldn't So had to unplug at the mains then then turn the power back on. After a few minutes it sorted itself out and the monitor came back online as though nothing had happened. Is this a general problem with HP? if so, we're going to return the equipment to the store and get something else!