Applications use the "wrong" IP address
I have a weird problem. My system has two network adapters, one with a 192.x address and one with a 10.x address. I connect to the Internet over a proxy that also has one 192.x address and one 10.x address. The name of this proxy is added to /etc/hosts with the 10.x address. Additionally, the network settings for the 10.x adapter include the proxy as gateway. The 192.x adapter has no gateway. If I ping the proxy, it is correctly resolved over the 10.x address.
All my applications are set to "directly connect to the Internet".
Some apps (the "good" ones) use the 10.x address to connect to the proxy, while some others (e.g. Firefox, the "bad" ones) use the 192.x address. The latter fail to connect to the Internet because the proxy is configured to let traffic through the 10.x adapter only.
Any ideas why some apps try the 192.x-way? I don't see any reason they should do this, see network config above.
P.S.: system is RHEL 5.5