I've noticed that on certain levels, my space bar will cease to work. It seems to fix itself once I move into a new area. At first I thought I was just not supposed to jump in those areas, as it didn't seem to make much sense why it would be fixed by an area change. The levels in which it wasn't working di, in fact have "jumpable" content.
I can't repro it, although it happens often. I'll try and dig deeper next test. My guess is that it's a Flash focussing issue.
I'm on:
Chrome 5.0.375.99
Snow Leopard 10.6.4