Sticky Keys won't turn on

Earlier today, my computer BSOD'd. After the restart, Sticky Keys was off, which was not how I had it set pre-crash.

I went to the Accessibility Options, clicked the box to turn Sticky Keys on, clicked Apply, then Okay, and... nothing. I can't get any other of the Accessibility Options to apply, either.

I'm not sure what caused the system to crash exactly, but it I was trying to remove a USB drive when it happened. I haven't noticed any other odd behavior, but my desktop reverted to the felt-green background color; I previously was using a custom image with a black background. I haven't noticed any other quirks. (Yet.)

I can't find much help online; has anyone ecountered a similar problem?

Using XP SP3 on this model: http://goo.gl/MlccR but I've doubled the memory and added a graphics card (though what kind escapes me at the moment).