top using full cpu core session/process management weirdness

[Dennis Jacobfeuerborn]

Hi,
I just stumbled over a strange phenomenon that makes top go bananas.

To reproduce open one shell window (and only one), switch to root and run 
"top". Now close the shell window (without quitting top first).
top will now suddenly start to use 100% of one cpu core.

Things get more interesting when multiple shell windows are involved.
I this situation top only goes bonkers once you close the last (!) shell 
window. As long as any shell window is still open the top process will 
still run but not use many resources.

Regards,
   Dennis