Depth Testing glitch

I''m working on a SceneGraph, and I implemented Depth Buffer Render States. The problem is it seems that if I call the function glDepthMask more than twice, you get a glitch (the more you call it, the worse it gets). I need to turn off Depth Writing when I draw particles. Basically, my main question is wether this is normal or not (driver issue?) I''m guessing I will have to sort my components so that I can draw all objects with depth writing before, and those without after. Thanks in advance for your comments