It is Firefox 22, just installed.
I just did a new version printing , dt is almost permanently at 0.1, way too high.
It seems a performance issue in my Firefox. Clean reinstall didn?t solve it. All plugins disable didn?t solve it. Whatever it is, affects just Firefox. It didn?t happened before v22.
However... Shouldn?t plataform work even with a high dt?
In my monitor, it seems to me that the Plataform (Red square) simply jumps past the solids (blue squares), probably because of large dt making large steps.
I am going to work, will check video drivers later.