Are you sure you do not have a "ip local pool" or a DHCP Server configured on your PIX ?
Check if you find this lines in your config:
1.)
ip local pool YOURPOOLNAME 192.168.1.x-192.168.1.x
if yes just remove it with:
no ip local pool YOURPOOLNAME 192.168.1.1-192.168.1.10
or you have a DHCP configured like that:
dhcpd address 192.168.1.x-192.168.1.x inside
dhcpd dns dnsIP1 dnsip2
dhcpd lease 3600
dhcpd ping_timeout 750
dhcpd yourdomain
dhcpd enable inside
Remove it:
[no] dhcpd address ip1[-ip2] if_name
[no] dhcpd auto_config [outside]
[no] dhcpd dns dns1 [dns2]
[no] dhcpd wins wins1 [wins2]
[no] dhcpd lease lease_length
[no] dhcpd domain domain_name
[no] dhcpd enable if_name
[no] dhcpd option 66 ascii {server_name | server_ip_str}
[no] dhcpd option 150 ip server_ip1 [ server_ip2]
no dhcpd option code
[no] dhcpd ping_timeout timeout
[no] debug dhcpd event
[no] debug dhcpd packet
show dhcpd [binding|statistics]
and then change your inside IP address:
sincerly
Patrick