[newbie] internet problems!

[kristijan lecnik]

hi! i have a wierd problem with my internet connection on LAN computers. i have mandriva 2006 instaled on my server, and it is a gateway for my computers on LAN, i have 3 others PCs with WindowsXP SP2 , on my mandriva i use shorewall to route internet to my LAN PCs. i used this on my erlier systems Mandriva 2005, and Mandrake 10.1 , and always it worked properly, but yesterday when i instaled mandriva 2006, and set up the shorewall, my LAN PCs cant acces some internet sites like: everything connected with msn.com, nero.com and more, other web sites are working, but there are many that doesnt works, but the mandriva 2006 can acces all the sites. so if you can tell me what to post here to help me out.