It sounds to me like what is actually occuring during fermentation is still "a mystery to you". Understanding what changes are taking place can help you to interpret and address your beer's condition at any given time.
Above is good advice re: hydrometers and time in the primary. You should also read or re-read Palmer's How To Brew
because it helps you to develop an understanding of the changes that are occurring - or in the case of your chocolate beer - not occurring.
My bet is you had a stuck ferment, that could've been solved by gently swirling the beer in the fermenter and leaving it for another 1-2 weeks.
Also, I'd recommend posting your thread in the correct forum next time - this one is for bugs related to the forum software. This thread is best located in the Beginners' Forum or in the General Techniques forum.
Cheers and thanks for sharing your story. Hope our advice helps a little. With some patience and studying, you'll be making non-explosive good beer in no time flat. Good luck mate!