Why is the system proxy refusing connection?

Question

I'm currently using Firefox 3.6. I usually connect to the internet through the system proxy, but for the past two weeks I have not been able to. The proxy works for every other computer connected to this network, just not mine. I can still connect if i change it to no proxy, auto-detect, or manual, but these give me connection problems especially when I'm trying to attach a file, run ymsg, or upload documents to anything.

Answer 1

The header of the Java Console for Both PC's say the same thing.
which is
Java(TM) Plug-in: Version 1.3.1_02
Using JRE version 1.3.1_02 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\Administrator
Proxy Configuration: no proxy
And the output for them are seen in my previous post.
This is the System properties for the javaplug in of the non-working PC.
java.vm.vendor = Sun Microsystems Inc.
java.vm.version = 1.3.1_02-b02
javaplugin.classloader.cache.enabled = true
javaplugin.console = false
javaplugin.debug.mode = false
javaplugin.enabled = true
javaplugin.exception = false
javaplugin.jit.enabled = true
javaplugin.jre.path = C:\Program Files\JavaSoft\JRE\1.3.1_02
javaplugin.jre.type = JRE
javaplugin.jre.version = 1.3.1
javaplugin.maxHeapSize = 96m
javaplugin.nodotversion = 131_02
javaplugin.proxy.config.type = direct
javaplugin.proxy.forallprotocols = false
javaplugin.proxy.usebrowsersettings = true
javaplugin.version = 1.3.1_02
and this is the java plugin system properties from the working
javaplugin.maxHeapSize = 96m
javaplugin.nodotversion = 131_02
javaplugin.proxy.config.type = direct
javaplugin.version = 1.3.1_02
So my question is Why would system properties be different for these 2 machines ? I am traking this as a possible explanation for why the Same application does not work on 1 pc but works on another pc - though they are supposed to have the same plugin .
Thanks in advance;
Stephen