IOS 4.3 - Authenticated Proxy + Wireless issues

Question

Okay, I can see a lot of similar titled posts, but none quite have the same issues as we are facing here, so I decided to create a post of my own.
What we have is an 802.1X (AD/RADIUS) wireless network configured (on the iDevices) as a "WPA2 Enterprise" network and using a self-signed certificate. Once configured we also specify an authenticated proxy for the connection. Now, we've supported iDevices here for quite some time without too many issues (aside from the other occassional issue with updated phones, etc). We have everything on our network from "iPhone OS 3.1.2" through iPads with "iOS 4.3" and have been very successful in supporting these devices in the past... until v4.3.
With the new update, we have devices that worked perfectly before (and have been correctly configured) now asking for a username and password when browsing in Safari. We have devices that, on entering the correct information, give us messages such as "Incorrect username or password" or "Unable to join the network <name>". The same devices worked perfectly with iOS 4.2.1 installed. We've tried;
a) Forgetting the networks and setting them up again.
b) Changing the user's password and setting things up again.
c) Resetting network connections and trying again.
d) Resetting the entire phone and trying again.
But to no avail. If you can get wireless configured without either of the above errors messages, it will simply fail to work with the proxy server and cause issues in Safari, etc.
This is emmensly frustrating. We've had to put out a notice to all users to NOT update to v4.3 until this is resolved... which is not cool.
Interestingly, we also had a 3G rock up to the helpdesk today. It had iOS 4.2.1 installed (the latest availaqble for that odel, apparently) and it was exhibiting the same sort of behaviour (and is the only non-4.3 device to do so).
Any thoughts. Do we just need to wait until iOS 4.3.1 to get this fixed (like last time)?

Answer 1

So, I updated a couple of iPads and a few more iPhones yesterday and today. Around 50% success rate - which is weird. Tried the hard-off, reset network, forget network type stuff again, and no joy. Here's an intersting thing though;
a) We can now tap on the SSID and it figures out that it's an enterprise network. Saves chosing the options after tapping the "Other" setting. This also appears to improve the success of accepting the certificate as well. Neat. This didn't used to work.
b) Although the setup looks good, and Exchange just works... we were STILL getting an authentication box in Safari and things were not working correctly. As a test we entered credentials (using email address format - which also appears more successful) and it didn't appear to fix anything, or so we thought. on entering the auth details in Safari, the page that requested it stayed 75% loaded and didn't looks to be working. On closing that window and trying others like "Apple", etc, it appears to work.
I have done this on all the devices that failed and so far so good. So, forget your current network, set up the new enterprise wireless by tapping on the SSID (don't configure using "Other"), enter credentials as email addresses, and authenticate in Safari when you are asked the first time. Reload the page and test.
While this shouldn't make any difference (and is similar to what we tested in v4.3.0), it appears to work for us at the moment.