Some websites, however, plan for errors, and try to support, not fight, the user's responses.
A good example is how Twitter helps the user recover from an incomplete action during the sign up process. In order to create an account, users are required to input a "security code" (which helps prevent automated programs from abusing the service).

Once you have entered the correct code, you are done with this step of the process--even if other fields have been incompletely or improperly specified:

Twitter's design choices lets the user easily figure out what to do to fix the problem, and show politeness and helpfulness by not only remembering the entered code, but also acknowledging to the user that this step of the process was successfully completed.
Take notice, impolite websites out there.
