defunct processes

[Nitin]

Hi again,

I'm facing this problem for long. Why do processes start to add in the list like following:

>>>>>>ps -ax |grep Z

15611 ?        Z      0:00 [awk <defunct>]
15645 ?        Z      0:00 [hostname <defunct>]
15647 ?        Z      0:00 [hostname <defunct>]
 2034 ?        Z      0:00 [awk <defunct>]
 2041 ?        Z      0:00 [mktemp <defunct>]
 5542 ?        Z      0:00 [chown <defunct>]
 7474 ?        Z      0:00 [sh <defunct>]
 7477 ?        Z      0:00 [hostname <defunct>]
 7481 ?        Z      0:00 [sh <defunct>]
 7484 ?        Z      0:00 [hostname <defunct>]
18934 ?        Z      0:00 [awk <defunct>]
  727 ?        Z      0:00 [awk <defunct>]
 6081 ?        Z      0:00 [sh <defunct>]
 6084 ?        Z      0:00 [hostname <defunct>]
 6117 ?        Z      0:00 [sh <defunct>]
 6120 ?        Z      0:00 [hostname <defunct>]
 6132 ?        Z      0:00 [sh <defunct>]
 6135 ?        Z      0:00 [hostname <defunct>]
 6140 ?        Z      0:00 [sh <defunct>]
 6143 ?        Z      0:00 [hostname <defunct>]
 6150 ?        Z      0:00 [sh <defunct>]
 6153 ?        Z      0:00 [hostname <defunct>]
 6180 ?        Z      0:00 [sh <defunct>]
 6183 ?        Z      0:00 [hostname <defunct>]
 6187 ?        Z      0:00 [sh <defunct>]
 6190 ?        Z      0:00 [hostname <defunct>]
 6194 ?        Z      0:00 [sh <defunct>]
 6197 ?        Z      0:00 [hostname <defunct>]
 6223 ?        Z      0:00 [sh <defunct>]
 6226 ?        Z      0:00 [hostname <defunct>]
 6228 ?        Z      0:00 [sh <defunct>]
 6231 ?        Z      0:00 [hostname <defunct>]
 6281 ?        Z      0:00 [sh <defunct>]
 6284 ?        Z      0:00 [hostname <defunct>]
 6288 ?        Z      0:00 [sh <defunct>]
 6291 ?        Z      0:00 [hostname <defunct>]
 6294 ?        Z      0:00 [sh <defunct>]
 6297 ?        Z      0:00 [hostname <defunct>]
 6303 ?        Z      0:00 [sh <defunct>]
 6306 ?        Z      0:00 [hostname <defunct>]
 6311 ?        Z      0:00 [sh <defunct>]
 6314 ?        Z      0:00 [hostname <defunct>]
 6318 ?        Z      0:00 [sh <defunct>]
 6321 ?        Z      0:00 [hostname <defunct>]
 6324 ?        Z      0:00 [sh <defunct>]


Why does it happen, plz help me as soon as possible. It's affecting system stability badly.

Thanks in advance
Nitin