Certain Windows sounds stopped working!

[YourNumbr1Fan]

Attachment 69706

I have no earthly idea what has caused this, but sometime today, while I was away from my pc, a few of my system-sounds just quit working! Restore Up, Restore Down, Minimize, and Maximize.

They were working fine earlier. I left my house to go pick up my wife from somewhere, left the computer on with the monitor shut off, came back.....and this.

I've tested those sounds (I'm using one of MrGrim's HUD Machine themes) from the Sounds menu, they are working. They test loud and clear. But, they won't work when I actually maximize, minimize, or restore an open window! I've also tried the default Windows sounds; same thing there, the same sounds don't work. All the other sounds do, except those.

Anybody had this happen before?