Well, I've owned it over a year, and it never has 'til now. I haven't fiddled with anything (that I know of), so why would it suddenly change its behaviour? This is what makes me worry whether something is on the blink. If it had always done it, no problem - but sudden changes, for no known reason?

From what you have said so far it sounds as if, for some reason, the SETI program stopped (or at least stopped using CPU cycles). Then, after a time, the laptop went into hibernation - which is its default configuration.

Why the SETI program stopped is another matter.

Four SETI processes were (and are) running - one per processor. So all four would have to have come to grief for the OS to rate the machine as "idle" (not to mention all the other little automatic housekeeping and maintenance tasks - not SETI related - that seem to go on at any hour of the day or night).

For all four processors to have encountered an event that rendered them "idle" is something of a concern in itself (there were no failed or suspended SETI tasks in the log of that).

I think the warnings about the restricted processor speeds were a red herring, as doing a more detailed trawl of the logs suggest they occur most days, if not all, and are probably a default part of routine operation, to prevent overheating. Sometimes they have happened several days in a row, at exactly the same time to the second, which implies they coincide with some particular scheduled process being run.

They've never previously been associated with the machine going into hibernation, or with any symptom at all. I would not have known about them, had I not been searching for clues to the unexplained hibernation.

T.

And yet - according to the log - the CPUs were idle. I think this is a software problem - not hardware or the OS.

Maybe the SETI processes did find some evidence - then tried to hide it...

I notice that on the SETI@home status page all the ap_splitter programs are listed as "not running". Could this have affected things? (The notes say "At least one needs to be running to produce work, and that's usually enough.")

If you go into the power settings and select the advanced option then there is a setting buried in there specifically for hibernate under the "sleep" twisty.

My understanding is that windows only considers the machine to be busy if there is human interaction - even if you set windows to do a massive file transfer it will still sleep/hibernate if you don't press any buttons/wiggle the mouse - and this is partly because windows always has something to do so what is considered "idle"?

But none of this makes sense in the context of what actually happened. It had never done it before, and hasn't done it again all of yesterday, or last night, despite nothing having been tweaked. If I have ever touched those settings at all, it would only have been in the first few days of owning the machine - over a year ago. So it's not "normal behaviour" - or certainly not "normal" for the way I've always had it set up, right from the word go. I've never wanted it to hibernate, precisely because it usually has some distributed computing project on-the-go. What better time to donate processing power than when I'm not at the machine? So I don't want it all to come to a halt, every time I'm not there.

It has been normal behaviour for the screen to be powered down after a few minutes unattended. That's as I want it, because I don't want the screen blazing away into the night, with nobody there to see it. But I've never needed to hit the power button when I return, so something was different this time. So much so, that I initially thought the computer had failed, and was relieved when it did restart - with no obvious signs of damage or corruption.

T.

Not disagreeing with anything you have said. However, if you check that setting is not set then it rules it out and may just have to be put down as a glitch (especially if the machine has been running 24x7 for a while as Windows does tend to like the occasional reboot).

My Dell Studio occasionally hibernates for no good reason. Most of the time I put it into Standby if I'm going to be out for a few hours and a tap of the touchpad wakes it up. But sometimes I can be away for an hour and when I come back it's hibernated. A tap on the power button wakes it and no problem, but it is a mystery. Can hibernation be disabled in Win7?