Could not reattach to shared memory

I am running postgres 8.3.7 on windows server 2008 SP1. But this error
alway occur : FATAL:  could not reattach to shared memory (key=260,
addr=02400000): 487
.Here is my log
2009-06-17 20:45:18 ICT LOG:  database system was shut down at
2009-06-17 17:42:45 ICT
2009-06-17 20:45:22 ICT LOG:  database system is ready to accept connections
2009-06-17 21:36:45 ICT LOG:  loaded library
"$libdir/plugins/plugin_debugger.dll"
FATAL:  could not reattach to shared memory (key=260, addr=02400000): 487
2009-06-17 21:36:48 ICT LOG:  could not receive data from client:
Unknown winsock error 10061
2009-06-17 21:36:48 ICT LOG:  unexpected EOF on client connection

When i run my application again and again, this error disappear. I have
NOD32 and add Postgres\bin\*.* to exclusions of NOD32.
My system :
Postgres 8.3.7
Windows Server 2008 SP1.
Postgres 8.4 beta 1 on other port.
Postgres 8.1 on other port.
NOD32

Sorry for my English
Tuan Hoang Anh
hatuan05@gmail.com