In the County Sewer Mainline area, there are two radroaches in a cage, the game freezes when I kill them

Don't kill the roaches. This is not an issue with the game, as this is not fixed with the Unofficial Patch, nor is it listed as an issue on the wiki. I can kill them with no problem.

So, running any mods? Using the same Autosave or save slot over and over again?

I'm playing the 360 GOTY version, and I managed to kill them using a grenade a moment ago without thg game freezing