The trouble with Protestantism

The first problem, slightly tongue in cheek, is seen in the name.  Anything ending in "ism" is automatically suspect.  But seriously, the suffix "ism" suggests a man made thought process.  And really, when you look at it, the entire Protestant movement, regardless of branch, is about a new interpretation of text.
The problem is much harder to nail down though.  Because the genre is so incredibly large and diverse, the categorization and identification will be difficult.  I think what it really comes down to is the ultimate rejection of authority.  Every single emergence of a new branch of Protestantism is because of a disagreement over the text of Scripture or a practice supposedly derived from Scripture.  Any and every branch of Protestantism lacks any real authority and the quasi authorities that are in place are always questioned.  What this means is that no one is an actual authority.  Protestants, almost by definition, appeal to Scripture as the final authority.  The problem with this is the seemingly endless malleability of the text.  And without an authority to say, "yes, it means this, no, it doesn't mean that," the possibilities are endless and there are almost no brakes on the situation.
So having no one to whom to appeal, the Protestant fragmentation continues.  At some point, the term "Christian" will almost be void of any concrete meaning.
I would encourage all Protestants to consider who is the objective authority in their life and then give consideration to the Eastern Orthodox church.  The faith of the church goes back to, and rests upon, the apostolic tradition as given by Jesus Christ.