If you've picked up a bouncing capsule item (as in level e3l06) on systems with a FPS below 100, jumping forward with it won't work everytime.
This bug is currently being removed!
Please stay patient.
A workaround is currently the ajustment of the line
in the script "data/init.mdef"
Just substitute the number indicated by the points by a huge number, e.g. 1000
However, this may result in falling trough solid blocks :-(