Arch Linux keyboard key repeat not working properly (typematic delay)

I'm having a very strange problem in Arch where holding down a keyboard key sometimes has no effect. Instead of auto repeating the key, it will do nothing at all. Holding down backspace, for example, won't erase more than one character.

I've tried using the command xset r rate delay [rate] but this is not sufficient to reactivate the key repeat. When the key repeat is working I can see that xset has changed the repeat delay, but it will still get stuck for apparently no reason. Once it gets stuck it is stuck in every program, but it will go away suddenly. Right now it's working as normal.

I'm running Awesome WM and recently installed compton-git. I didn't notice the problem before installing it, but I can't imagine how compton could possibly make my key repeat stop. I'm also using a cooler master mechanical keyboard with a PS/2 adapter instead of plugging it into USB. I dual boot Windows 7 and have never had the problem there.

I've had no success searching for a solution. Does anyone know of any xorg configuration files that might control this behavior?