Yikes!!! My mouse pointer is stuck!
This has actually never happened to me before, but on the off chance that it happens to someone else, here's what happened and what to do when your mouse pointer (sometimes called "the cursor") locks up on you. I'm using a Toshiba notebook computer, and the specific techniques will vary with other models and brands, but at least you know the general problem and can try similar solutions.
So, everything was fine and then I hit a control key sequence and things went crazy.
First, I meant to hit Alt+Space+X to maximize a window and accidentally hit Fn+Space, which magnifies the screen. I had never done that before, so it really freaked me out visually. It took me a while to figure out which key I had actually hit since I had thought that I hit the Alt key. It turns out that simply hitting Fn+Space two more times restored the magnification to its normal view.
But before I figured out how to resolve that minor problem, I had noticed that my mouse pointer (sometimes called "the cursor") was stuck. No matter how I moved my finger on the touchpad, the pointer simply wouldn't budge. The combination of this problem and the preceding problem (I'm not sure which I encountered first since they occurred right after each other), I tried the trusty technique of shutting down (using the keyboard since the touchpad was a no-op) and rebooting. It didn't help. The mouse pointer was still stuck.
I was fairly confident that the mouse pointer stuck when I was trying to type some Ctrl key sequence and must have hit Fn rather that Ctrl. So, I tried all the Fn keys, which are labeled in gray on the keyboard, but I didn't see any affect on the mouse pointer. Thinking that maybe there could have been a coincidence and maybe some hardware glitch occurred at the same time as the other problem, I power-cycled again. No help.
I even tried accessing the control panel applet for the Mouse using the keyboard only and even went through the troubleshooter, but still nothing.
Then I examined the system tray in the Start bar since I know there is some touchpad control feature there. I found the box-like system tray icon that controls the touchpad and noticed that it had a red X through it, strongly suggesting that the touchpad was indeed turned off. But without a working mouse, I could see no obvious way to get to that control and turn the pointer back on.
Convinced that it was an Fn key sequence that got me into trouble, I went back to examing the gray Fn key labels looking for something that looked like that touchpad icon. None of the box-like key labels seemed to control the touchpad. Then, I noticed that the gray key label on the F9 key actually looked like an upside-down two-button mouse. Actually the icon is even more confusing to figure out since it consisted of two of those inverted mice with a slash between them a slash in a circle over them. Looking back, I can see the "logic" of that key symbol, but without careful thought, visually it didn't look apparent at first glance. I took a deep breath and tried it... it worked! Toggling Fn+F9 toggled the red X over the touchpad icon in the system tray. I think I missed it before because I basically hit each Fn key twice to see what it toggled and then to return the toggled value to what it was before it was toggled and I hadn't looked at the touchpad icon in the system tray to notice its state when I hit the key.
I was getting rather freaked-out there for about five minutes, but everything is fine now.
So, even if you are "a Mac guy", you could really become someone's "hero" if you're on a plane or in a meeting or coffee shop and somebody accidentally hits Fn+Space or Fn+F9 and is now dead in the water and only you know the magic secret key sequence to restore their sanity.
And you Mac guys... no need to comment about how you never have these kinds of problems... this kind of thing rarely happens to me and now that I made it through those five minutes of hell, life is wonderful again, for now.