Screen Saver Glitch

Cool screen saver video, because sea turtle.
My computer is set up to turn off the screen after so many minutes. I think it's called 'Power Save' mode or some such. It's been very reliable up until a couple of days ago when it started getting slow to wake up. Used to be all I would have to do is bump my desk or set something down on it and the computer and the screen would wake up. Now it takes a deliberate action. I have to slide the mouse like a foot across the desk before things wake up and I'm wondering what's going on. Is the display getting flaky and it now takes seconds before the wake-up signal manages to actually turn on the power? Or has some kind of virus infected my computer and the NSA is now tracking my mouse movements? Or maybe it was just some kind of automatic software update. While an update would be good in that it means the display is NOT flaking out, I wonder what it could be. This is a Windows XP machine and I thought Microsoft was done updating XP, never mind that I thought I had updates turned off. Firefox just updated itself, again, but I don't see how that could have anything to do with this, although it's a stupid Windows computer, so anything is possible.