I seem to be having the same problem.
Strangly only happens on certain programs (eg grsync and terminal) and not others (eg gedit and nautilus).
When it happens my system is not workable, the empty help page forces itself on the foreground. It closes upon Quit or Force Quit from launcher, but immediately opens again.
I can move other open windows, but can't use them since the help page sort of 'forces itself' and doesn't allow input in other apps. CPU load goes up, due to yelp and xorg, but not to 100%.
Typing 'yelp' in terminal without arguments works fine, except for several repeats of this message:
** Message: console message: @0: event.layerX and event.layerY are broken and deprecated in WebKit. They will be removed from the engine in the near future.
(don't know what that means)
I want to backtrace, but since everything works fine from terminal there's no real use, so I was wondering what arguments yelp needs to display specific help info (eg for grsync)? Without arguments 'Ubuntu desktop guide' is displayed and everything is fine.
I'd appreciate any help, thanks
Precise Pangolin 64-bit, Kernel 3.2.0-24-generic, Intel® Core™ i5-2430M CPU @ 2.40GHz × 4, AMD Radeon HD 7400M Series on a Sony Vaio laptop