I find the idea of having a large number of half-independent, half-intelligent tiny robots exploring and mining our solar awesome and exciting. Soon they'll be self-duplicating, after all, that saves a lot of money over sending new ones up! Humanity will have millions of little workers out there, sending down resources, progressively further developed. At some point, much of our goods could be coming from space!
Meanwhile, a few stray ones with broken communication modules will get lost but continue to duplicate. The radiation will modify the code they are running, and where it doesn't impair duplication, become part of the new versions. Sometimes, a modification will give one a head start over others, allowing it to take the resources it needs for duplication - perhaps with force. Soon after, the strong will start to prey on the weak and 100 years from now, earth will be invaded by a swath of intelligent little killer bots.
Interesting, I haven't seen a SF book exploit this possibility - yet it now seems the most likely way of a human-AI war to go ;-)