Noticed this problem last night while watching a movie via usb stick. PS3 connected via HDMI lead - the picture started flickering and dropping out - coming back on - then eventually going completely blank with no output detected.
I then noticed that the hard drive light on the PS3 was blinking like mad - when it stopped, the PS3 screen came back on - no messages etc.
I then started watching the film again, and this fault reoccurred a further 3 times before I gave up.
I checked the HDMI lead was secured properly at both ends, and cannot think of any other reason for the failure - checked for any updates, none available.
Anyone got any experience of this, unsure as to whether the machine is under warranty or not.