I drew this topology in Boson NetSim 6.

and the configuration as below.
What's weired is that I see on "router1" in "sh ip route" that network 192.168.20.160(the switch2 ethernet) is accessible via "192.168.20.161" instead of "10.1.1.6"! how come? can someone tell me what I did wrong?
Another problem: From pc1, I can only ping interfaces on router4, can't ping others. What's wrong?
router1:
!
interface Serial0
ip address 192.168.20.33 255.255.255.224
no ip directed-broadcast
clock rate 64000
!
interface Serial1
description to Router5
ip address 10.1.1.5 255.255.255.252
no ip directed-broadcast
clock rate 64000
!
interface Ethernet0
ip address 192.168.20.97 255.255.255.224
no ip directed-broadcast
ip ospf priority 0
!
interface Ethernet1
ip address 192.168.20.65 255.255.255.224
no ip directed-broadcast
!
!
router ospf 3
network 10.1.1.0 0.0.0.255 area 0
network 192.168.20.0 0.0.0.255 area 0
!
ip classless
no ip http server
!
router2:
interface Serial0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
interface Ethernet0
ip address 192.168.20.126 255.255.255.224
no ip directed-broadcast
!
interface Bri0
no ip address
no ip directed-broadcast
shutdown
!
!
router ospf 9
network 192.168.20.0 0.0.0.255 area 0
!
ip classless
no ip http server
!
router3:
interface Serial0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
interface Ethernet0
ip address 192.168.20.94 255.255.255.224
no ip directed-broadcast
!
interface Bri0
no ip address
no ip directed-broadcast
shutdown
!
!
router ospf 400
network 192.168.20.0 0.0.0.255 area 0
!
ip classless
no ip http server
!
rouer4:
interface Serial0
ip address 192.168.20.62 255.255.255.224
no ip directed-broadcast
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
interface Ethernet0
ip address 192.168.20.129 255.255.255.224
no ip directed-broadcast
!
interface Bri0
no ip address
no ip directed-broadcast
shutdown
!
!
router ospf 120
network 192.168.20.0 0.0.0.255 area 0
!
ip classless
no ip http server
!
router5:
interface Serial0
ip address 10.1.1.6 255.255.255.252
no ip directed-broadcast
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
interface Ethernet0
ip address 192.168.20.161 255.255.255.224
no ip directed-broadcast
!
interface Bri0
no ip address
no ip directed-broadcast
shutdown
!
!
router ospf 8
network 10.1.1.0 0.0.0.255 area 0
network 192.168.20.0 0.0.0.255 area 0
!
ip classless
no ip http server
!
switch1:
hostname switch1
!
!
!
!
ip address 192.168.20.150 255.255.255.224
ip default-gateway 192.168.20.129
!
switch2:
hostname switch2
!
!
!
!
ip address 192.168.20.165 255.255.255.224
ip default-gateway 192.168.20.161
!
PC1:
interface Ethernet0
ip address 192.168.20.135 255.255.255.224
no ip directed-broadcast
!
!
ip classless
no ip http server
!
ip route 0.0.0.0 0.0.0.0 192.168.20.129
!