Sometimes during longer games, it would run out of memory, leading to missing images, or the game just stopping to respond to mouse commands.
You could see the actual error message if you run a game like this (from readme):

"java -Xmx1200m -jar csp.jar"

What I did to resolve this, was just switching to 64bit Java VM (and uninstalling 32bit one), and starting it from the console like this:

"java -Xmx2400m -jar csp.jar"

Obviously, this would not work if you use an older 32bit Windows machine.

Bumping that 1200 up a little can help.  Though I didn't want to complicate anyone's life with complex 64bit installation instructions or memory settings that are beyond what an average machine can do, so I left it as is.  By far the easiest way to get around the OOM issues is to restart the game every now and then between matches.  Out of curiosity, how long do you have to play before you see it happen with the default settings?

Not sure. But what I noticed is that a lot of restarts or loading saved games will lead to issues earlier.

Unfortunately due to the nature of 32bit JVM you can not bump it much over 1200. For example, at one point game started with 1400, and then later it would not, etc...

Also beware just double-clicking the jar file directly will not give the game any memory parameters, and with the more common JVMs that will run out of memory super fast.