Sticky keys, the bane of generic keyboards everywhere.
This is the main reason why i stick with Microsoft or Logitech for my KB's. Smoother, quiet, reliable opperation, with no sticking, and no binding. Plus they usually last a good few years.
Hell, i even lost one of the springs in my space bar on the KB im currently useing (MS Internet KB Pro, good KB, will never know why they discontinued it), and it still works bueatifully. Not to mentiont eh years of abuse its recieved from LANning over the last 5 years.