restart hot corners

On Snow Leopard (latest version, but it's been happening for a while), I have the top right corner set to show Spaces, and the bottom right to show the Desktop. Occasionally, often enough to be annoying, and without any reason I can discern, these hot corners stop working. I have tried: * changing the action of the hot corners, mouse in (nothing happens), then change back * turning off Spaces and turning it back on * toggling the Spaces icon in the menu bar (worth a shot, right?) * killall Finder * killall Dock * killall SystemUIServer None of these work. If I close the MacBook to suspend it, then bring it back up, that fixes the problem, but is less than ideal if I have, e.g. a big download going. Is there a way to quickly (i.e. not log out/log in, not restart) fix the hot corners? Is there some special program I don't recognize in the System Monitor that will restart the hot corners if killed? Is there something that suspend recycles that I can recycle without suspending?