Fluid Sim Obstacle Bug

Hi - only been using Blender (which I love) for 6 months or so, so apologies if this has been covered elsewhere…

I’ve set up fluid sims in the past without any problems. Currently using 2.69 and everything works fine until I add an obstacle at which point when I bake the scene (v. simple, just icosphere inflow, cube domain & another cube as obstacle), it just bakes the first frame and the fluid remains static. Remove the obstacle and everything works again. Thought it might be a cache problem, so deleted it each time and still no joy.

Anyone know if this is a bug or am I just being dumb (v. possible)?

Thanks.

Obstacle was too small. Simples.