The scenario you are asking is a "classic" one. This question is one of the most frequent asked questions at QA interviews. Maybe this is why quite many articles, blogs are discussing about the possibilities and scenarios, like this, this or this.
I think, for your first question you can give yourself the answer by reading those pages. Just a suggestion: there always is another test case which can be run.
As for the second question, I think, that is the scenario which is named bug or failure. There is a "path" which can be found in any testing documentation: a failure or a bug is the result of an error. An error causes a fault which results a failure. Now, it seems that you found one. So the next step is to report the problem: report ID, date, version, name of the tester, environment specification, steps and the result vs expected result.