PostgreSQL Service unexpectedly closing

Question

using PostgreSQL 9.2 on Windows Xp(RAM 4GB) sometimes the Database service is closing unexpectedly.
am new in PostgreSQL Database, So i cannot figure out the reason behind it, can any one help me ?!

1. log 1
2. log 2

Current Backend Access config(pg_hba.conf)

host     all     all     0.0.0.0/0   trust

Postgresql.conf Settings

effective_cache_size  =  131072
lc_messages  =  English_United States.1252
lc_monetary  =  English_United States.1252
lc_numeric  =  English_United States.1252
lc_time  =  English_United States.1252
listen_addresses  =  *
log_destination  =  stderr
log_line_prefix  =  %t 
log_timezone  =  Asia/Calcutta
logging_collector  =  on
max_connections  =  10000
max_files_per_process  =  1000
port  =  5432
restart_after_crash  =  on
shared_buffers  =  131072
temp_buffers  =  131072
TimeZone  =  Asia/Calcutta
work_mem  =  1048576