Some U.S. commanders in Iraq and Afghanistan, despite admonitions from above, and clear instructions to the contrary, continue to try and treat their contractor personnel as troops. Some commanders insist that some of their contractors wear U.S. battle uniforms. By law, contractors are supposed to wear clearly different (from U.S. uniforms) attire, so that they can, according to international law, be easily identified as civilians. The errant commanders like to consider their contractor personnel as additional troops, if only they can be shaped up and disciplined. To this end, some contractor personnel are made to stand (in a military) formation when receiving instructions.
Naturally, this doesn't work on those few contractors who are authorized to handle weapons, as these are almost always former military or police, and know exactly what their status is. These guys tend to be the most disciplined contractors. It's the many without any military experience that can be the most troublesome. Some of these guys try to get weapons, even though they are usually not qualified to use one, and make themselves more of a target to hostile gunmen by carrying one.
All this is more dangerous in Afghanistan, where leaving your base is not as dangerous as it was in Iraq. Military commanders who pay attention, make sure their contractors know the rules, and obey them. But for those contractors who are poorly supervised, and feeling adventurous, the opportunities for misbehavior, and worse, are quite high.