I have also been having the same problem: I got a new PC, but am using an old monitor (that has been on the top of a shelf collecting dust for some time now). Recently it has started having a similar problem. Every once in a while, it gives this weird *click* noise, goes off for half a second, then comes back on. When it happens, it happens in clusters...like it may happen 10 times in 5 minutes, then the entire day (like today), it has no problem at all.