So, I gritted my teeth and went straight towards the cause of the strobing, and the first cause I identified was the hazy, propane-flame-like exhaust that is discharged underneath Mr. Gutsy robots. As soon as I kill the robot and the emissions stop, the strobing goes away. Since then, I have identified several other causes of this affect, including enemies that are actively using stealth boys (again, a hazy, ephemeral kind of special effect), such as the Nightkin; and the greenish explosions from pulse grenades or the Meltdown explosion affect. It's only these hazy, amorphous kinds of special affects that cause the strobing on my screen.
I updated the drivers on my ATI Radeon 5870 card recently, so I'm sure it's not old drivers. Any thoughts or ideas?