Can't maximize windows to second monitor

[nite_monkey]

Recently I was doing some "organizing" on my computer (moving icons to organized folders, getting lazy and then just putting them all back where they were), and I noticed that I can't maximize windows to my second monitor anymore. When I hit the maximize button, it maximizes the window to the left half of the screen, not the whole screen. I don't have any desktop enhancement programs, other than google desktop. Though I am going to see if I can get the Nvidia properties dialog to open so that I can see if the grid thing some how got turned on or something, but I don't think that is the problem, because to use the grid, you have to hold down the alt key when you maximize the window, other wise it maximizes to the whole monitor.

I would really appreciate it if someone could help me out here.

Edit: I don't have the Nvidia grid turned on, so it can't be that.

[cranioscopical]

You don't have monitors 1 & 2 switched around in your display settings do you?

[nite_monkey]

I have the monitors set up the same way they have been for the past couple of years, and with the current setup, it has worked perfectly in the past.

edit: ok, I would still like to know what the problem is, but I fixed it by moving my second monitor to the other side of my primary one, saving the settings, and then moving it back. I just wonder what caused it to do this in the first place, and how long it will stay fixed.