Multipoint videoconference problem

Question

We have in our company(ISP) a videoconference network that consists of 35 videoconference points connected to a central point consisting of a Cisco 7200 gatekeeper, a Cisco IP/VC 3540 videoconference system with a MCU MC06A. The equipment from these 35 points are 23 ViaVideo II systems, 10 PictureTel 550 video systems and 2 PictureTel 600 Series video systems(from 2 main points). Ok. What is the problem? A videoconference session is taking place with all these 35 points connected(without problems). Surposing site number 2(a ViaVideo) is talking with one main site(a PictureTel 600) but suddenly a crashing noise appears(for less than 1 second) and video switchs to another site, for example site number 24. We see that site number 24 doesn't have his microphone connected. After some minutes it happens again and video switchs to another site(only video - audio is muted at that site). Something it's going wrong. All sites have good connection between them.
Any idea what's the matter? Or where I can found exact information about this?

Answer 1

! No configuration change since last restart
version 12.2
no service pad
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec
service password-encryption
hostname Video-GK
logging queue-limit 100
enable secret xxxxxxxxxxxxxxxxxxxxxxxxxxx
username admin privilege 15 password xxxxxxxxxxxxxxx
clock timezone EET 2
clock summer-time EET recurring last Sun Mar 2:00 last Sun Oct 3:00
clock calendar-valid
ip subnet-zero
ip cef
no ip domain lookup
ip domain name xxxxxxxxx.xx
ip name-server x.x.x.x
ip name-server x.x.x.x
no ip bootp server
no voice hpi capture buffer
no voice hpi capture destination
mta receive maximum-recipients 0
proxy h323
interface FastEthernet0/0
description -= Local Switch 2690G Link =-
ip address x.x.x.x 255.255.255.240
ip route-cache same-interface
load-interval 30
duplex full
speed 100
no cdp enable
h323 interface
h323 qos ip-precedence 4
h323 h323-id Video-GK-proxy
h323 gatekeeper id Video-GK ipaddr x.x.x.x
h323 t120 bypass
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
no cdp enable
ip classless
ip route 0.0.0.0 0.0.0.0 x.x.x.x
no ip http server
no cdp run
call rsvp-sync
mgcp profile default
dial-peer cor custom
gatekeeper
zone local Video-GK MTC_Video x.x.x.x
lrq forward-queries
no use-proxy Video-GK default inbound-to terminal
use-proxy Video-GK default inbound-to gateway
use-proxy Video-GK default inbound-to mcu
no use-proxy Video-GK default outbound-from terminal
use-proxy Video-GK default outbound-from gateway
use-proxy Video-GK default outbound-from mcu
no shutdown
banner incoming ^C +++ Welcome to Cisco 7200 Video Gatekeeper +++ ^C
banner login ^C +++ Welcome to Cisco 7200 Video Gatekeeper +++ ^C
line con 0
stopbits 1
line aux 0
stopbits 1
line vty 0 4
exec-timeout 0 0
login local
ntp clock-period 17180162
ntp peer x.x.x.x
end