I've found that there's some kind of bug that causes the client to crash if you get too close to the bottom layer of bedrock. I'd recommend staying away from that. It's not so bad, though. The game is perfectly fine when restarted. It's just inconvenient.
Though computers from OpenComputers will remember where they were in execution (as well as values of variables) when their chunk is unloaded (including exiting map / closing server for multiplayer), be cautious of the robot.swing() function for block breaking. If a robot begins the swing action but does not complete it before its chunk is unloaded, the robot will resume after the robot.swing() function, and the block will not have been broken.
I've used the following cheap fix for this:
robot.swing() if robot.detect() then robot.swing() end
This will ensure that the robot will get a second chance to break the block when the chunk is reloaded.
If you're having issues with the difficulty of Realistic Torches (wherein torches burn out and have to be relit) and have monsters spawning in your house, I recommend the Electric Age lights. Even when off, Electric Age lights prevent monsters from spawning in a 9 block radius, meaning you can even turn the lights in your house off when you're not using them to conserve power without the fear of monsters spawning inside.
If you're using the server download and the exe is crashing, check and see if you set the eula value (in eula.txt) to true.