When i am exiting from an application getting Panic Cone 8.

According to Sdk Panic cone 8 defined as
"Environment found window server resources had not been freed
"
I gone through all the forums & sites and found that the main cause for this panic relates with Icons
used in the listbox.

I am using graphic listbox which have icons but its all working fine(reviewed it many times )

My querries are:

what are the resources does window server own(like icon).

what are the different cases in which cone 8 panic occurs


Any help or information are appreciable .

Thanks