Longtime subscriber James Biddle wrote to comment about a tip last week and to ask about an unusual event on his computer:
Great tip on indexing. I had a similar problem.
I have something strange that happens every once in a blue moon. I put my computer to sleep (I never shut it off). The only way to wake it up is via the start button. You can wiggle the mouse or hit keys all day–it won’t wake up. But every so often I ‘ll wake up (I too need a start button) and find the computer has magically switched itself on! Just curious what can cause it?
Since James didn’t mention what operating system he was using, my first response was to suggest that he might be using Windows XP. There were some hibernation and sleeping bugs in XP that caused strange problems, such as failure to go to sleep, and failure to wake up from sleep or from hibernation. These weren’t normal for all computer, but they did happen with some frequency on the computers that were affected.
James responded that he was using Windows 7.
At this point, I realized that he was talking about the computer waking up without other intervention, as opposed to not going to sleep. That makes me think that it is related to the programs he is running and the Windows scheduler..
Some programs, like Acronis True Image Home 2011 and 2012, can wake a sleeping computer to do the backup. It’s configurable whether it does it or not. Similarly, some disk defragmentation programs will do this.
There are also hardware ways that computers can wake up — some network cards have "wake on LAN" capability, where an incoming packet on the local network can wake up the computer. Since almost all hardware uses "switches" now and not "hubs", it would be an incoming packet that was directed specifically to that network card in the computer.
Switches pay attention and remember the MAC (Media Access Control) address of the network cards connected to each of their ports, and only send a packet to the appropriate computer’s network card. Hubs, on the other hand, broadcast every packet to all computers connected to the hub.
I suspect that James has a program that is set to run during the night and to wake the computer from its sleep state in order to run. The benefit of this type of schedule is that it happens routinely without disturbing you.