So after finding that one of my dock icons appeared pixelated, I recently experienced some of my dock icons become invisible.

I’m not sure what caused it although I think I was running low on disk space at the time so it may have been memory related. All I did to fix it was re-drag the application into the dock and the icon reappeared. There’s also a discussion in the Apple support forums about disappearing icons.

No idea why or how this happened.

Seemed to happen not long after upgrading to OS X Snow Leopard. Had a search around and found other people had been experiencing blurry/pixelated dock icons too. Also, this thread on the Apple Support web site.

Anyway, I just dragged the Safari application into the dock again and that fixed it for me – weird…