Some kind of black & white cam.
The splash screen is very white booting to 'play' & white on gray to 'rec'.
The IXUS 310 loads it's own custom colours into the Canon palette in the load_chck_palette function.
It has all of the standard CHDK colours correctly defined.
Are you using the version from the auto build server or compiling it yourself?
If you are compiling it yourself, have you tried the auto build version?
What firmware version is the camera?