LARTC - Feb 2007 - load balance problem

Hi friends;

i`m having troubles with load balance, i follow the lartc howto,
aparently everything works fine, the firewall selects the right link
when the other is down, but when i try to use clients (windows) some
pages open without pictures, some not, when i "ping" somewhere 50% of
the packages are lost,sometimes dont "ping"... this firewall only do
nat .. without any rule, without squid... the firewall show some logs
on terminal: "MASQUERADE: Route Send us to somewhere else" , where are
my mistake??  any help??  tanks a lot!!

JC Junior