After upgrading Firefox 17.x to version 18.0.1, the ONLY site that will connect and can run is Google. Attempts to connect to any other DNS results in a tab displaying the label 'Connecting', with an hourglass circle. After rolling-back to Firefox 17.0esr, all connections succeed using the same proxy settings.
Functionality in Firefox 18.0.1:
After all that, I uninstalled Firefox, deleted personal data and installed Firefox 17.0esr. Using the default 'use system proxy settings' network setting, it works perfectly. After upgrading to 17.0.2, it still worked.
When entering an IP address (to test whether it's a DNS resolution issue), 17.0.2 would work and 18.0.1 would still fail, leading me to conclude that the issue is a software bug rather than a proxy problem.
Have the Developers any input as to what may be different between 17 and 18 with regard to basic conectivity?
NB: I should note that I have already trawled through the generic connectivity troubleshooting steps Mozilla provide, as well as the help articles for situations in which Google is the only accessible site, and various other troubleshooting suggestions I found when searching. All signs point to the issue being a bug in this version.
Here is the Troubleshooting Information from 18.0.1:
User Agent Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/20100101 Firefox/18.0
Important Modified Preferences
Adapter Description NVIDIA GeForce 9300 GE
Adapter Drivers nvd3dumx,nvwgf2umx,nvwgf2umx nvd3dum,nvwgf2um,nvwgf2um
Adapter RAM 256
Device ID 0x06e0
Direct2D Enabled true
DirectWrite Enabled true (6.1.7600.16972)
Driver Date 10-2-2012
Driver Version 22.214.171.1247
GPU #2 Active false
GPU Accelerated Windows 1/1 Direct3D 10
Vendor ID 0x10de
WebGL Renderer Google Inc. -- ANGLE (NVIDIA GeForce 9300 GE)
Incremental GC true
Prevent Accessibility 0
Expected minimum version
Version in use
NSPR 4.9.4 4.9.4
NSS 126.96.36.199 Basic ECC 188.8.131.52 Basic ECC
NSSSMIME 184.108.40.206 Basic ECC 220.127.116.11 Basic ECC
NSSSSL 18.104.22.168 Basic ECC 22.214.171.124 Basic ECC
NSSUTIL 126.96.36.199 188.8.131.52
Unfortunately I've effectively covered the steps there.
I skimmed through the remaining sugesstions, but they all relate to infrastructure faults, of which there are none. The issue is very likely caused by a software change, as the immediate previous iteration of the product worked.