block file extension download not working with L3 vlans

Dear all

i have L3 switch (extreme switch) , with L3 vlans, i made IPForward between the vlans

vlan A 172.16.40.1

Vlan B 172.16.50.1

Vlan D 192.168.30.1

my firewall is having IP 192.168.30.2 and the internal port connected to Vlan D, also i made route in the firewall 172.16.0.0 to 192.168.30.1

routing in my switch is 0.0.0.0 to G/W 192.168.30.2

all functions in the firewall are working (web and application) except file download, for example if i tried to install SKYPE from Vlan A with desktop IP 172.16.40.5 and the gateway is 172.16.40.1 the file is downloading and not blocked by firewall, i made the policy to block all download in web profile.

i want to block the files and use internal IPS and IDS without changing my setup on desktop, also i don't want to use proxy mode in the firewall.

thanks