trouble with http

Hi I have a special problem. I use Suse 8.0 with Susefirewall2 and Squid 2.4. The main idea is a firewall with transparent proxy. With one windows client and Internet Explorer i want go into the internet My problems are: 1. If FW and Squid (transparent settings) are running: Browsing with IE is ok but i can't download any files. 2. If FW and Squid (without transparent settins) are running: Browsing with IE is ok but i can't download any files. 3. If i go directly to the Internet (without proxy an FW). I can't browsing with IE and i can't download any files. Grazy is, if i run iptraf, then is all ok. What's that??? Thanks for answer Gabriel