PR_Write(68) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)

Hello,

I have a Red Hat Directory Server 8.2.11 B2013.315.2031 on Red Hat Enterprise Linux Server release 5.7 (Tikanga)
Linux example.org 2.6.18-274.el5 #1 SMP Fri Jul 8 17:36:59 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux

Sometime I see these error logs:

[18/Mar/2014:18:24:38 +0100] - PR_Write(83) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[18/Mar/2014:18:24:58 +0100] - PR_Write(88) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[18/Mar/2014:18:37:54 +0100] - PR_Write(72) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[18/Mar/2014:18:40:46 +0100] - PR_Write(79) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[18/Mar/2014:18:40:50 +0100] - PR_Write(86) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[18/Mar/2014:18:40:52 +0100] - PR_Write(86) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[18/Mar/2014:18:41:38 +0100] - PR_Write(159) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[21/Mar/2014:09:48:19 +0100] - PR_Write(79) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[21/Mar/2014:09:49:09 +0100] - PR_Write(76) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)
[21/Mar/2014:10:04:26 +0100] - PR_Write(66) Netscape Portable Runtime error -5961 (TCP connection reset by peer.)

I can't understand why this happens. Unfortunately when this happens many applications which are using LDAP crash or stay stalled (as saslauthd and dspam).
I think that for few minutes LDAP doesn't work and write that errors on errors log.

This LDAP server is a consumer, it receives replica from a master server.

Could you help me to understand what is the reason of these errors?

Thanks a lot
Marco