chan_dahdi.c: Read failed with -1: Unknown error 500

[ShamanS]

I'see in /var/log/asterisk/full

[2015-07-09 13:33:53] WARNING[3380] chan_dahdi.c: Read failed with -1: Unknown error 500

what is is???

config:

 Kernel
   Linux(i386)-2.6.18-406.el5

 Elastix
   elastix-2.5.0-1
   elastix-a2billing-1.9.4-7
   elastix-a2billing-callback_daemon-1.9.4-7
   elastix-addons-2.5.0-3
   elastix-agenda-2.5.0-1
   elastix-asterisk-sounds-1.2.3-1
   elastix-email_admin-2.5.0-1
   elastix-endpointconfig2-2.5.0-1
   elastix-extras-2.5.0-1
   elastix-fax-2.5.0-1
   elastix-firstboot-2.5.0-1
   elastix-framework-2.5.0-2
   elastix-im-2.5.0-1
   elastix-my_extension-2.5.0-1
   elastix-pbx-2.5.0-1
   elastix-portknock-0.0.1-0
   elastix-reports-2.5.0-1
   elastix-security-2.5.0-1
   elastix-sugarcrm-addon-5.2.0l-9
   elastix-system-2.5.0-1

 RoundCubeMail
   RoundCubeMail-0.3.1-12

 Mail
   postfix-2.3.3-7.el5
   cyrus-imapd-2.3.7-16.el5_11

 IM
   openfire-3.7.1-1

 FreePBX
   freePBX-2.11.0-19

 Asterisk
   asterisk-11.17.1-1
   asterisk-perl-1.03-0
   asterisk-addons-11.17.1-1

 FAX
   hylafax-4.3.11-1rhel5
   iaxmodem-1.2.0-2

 DRIVERS
   dahdi-2.10.0.1-3
   rhino-0.99.6-4.b4
   wanpipe-util-7.0.12-3