its a very simple
the problems comes when you draw curve line, when you draw strait curve never comes the problem.
when you draw curve line over any objects or draw any illustration by pen tool.
when you start one point to another point with curve, automatically exist 2 handle for maintain roundness (curve).
Pls. again back go over last point and click over anchor point with option, pan tool automatically worked as convert point, now your suffix curve handle break and fix and again make next point with curve, and follow same option click over for break suffix handle.
above answer is true in my knowledge so I shared own knowledge with you. I am working photoshop last 20 years photoshop version 2.0 to upgraded version cs6