nulldata 500
 function bundle pippo(scalar n)
      bundle pluto
      matrix x = I(n)
      pluto["mymat"] = x
      return pluto
 end function
 bundle pluto = pippo(3)
 bundle pluto = pippo(4)
 Click on the bundle from the "session icon view".
 Gretl quits with a segmentation fault error. 
If it may help, I confirm the same
behaviour on Vista but gretl simply 
crashes with no error message.
Instead, it seems that the problem occurs when adding a new item - 
pippo(4) - in the bundle. Before that the bundle works fine.
Artur