Acrobat Standard Proxy Authentication

Question

Hi,
When we sign our PDF's we want to use an external timestamping server
So we have configured both a Verisign and Globalsign timestamping server and made one of them as default
Most of the time we got a response from Acrobat saying
"Timestamp signature property generation error:
Transport authorization failure"
When it fails the doc is signed, but using the computers clock and we want to avoid that
But sometime it did work which confused us but I think we have identified the problem with the Proxy authentication
Our proxy requires full authetication against our Active Directory
So when it worked was just because we just before signing had been surfing on the internet and the proxy had cached the credential approvals
So when Adobe tried to get out to the timestamp server the ID was already authorized in the proxy
But without a previous "IE-surfing" it fails, the proxy has nothing in its cache
A network trace confirms this,  we see a "Authentication required" request from the proxy that Acrobat never responds to
The proxy does not accept annonymous requests
IE is configured to use a configration script for its proxy settings
I cant find any relevant Acrobat settings that handles this and googling indicates that Acrobat has problems in this area
But I haven't found anything for our version/release
Now for the question, is Adobe Acrobat Standard 9.3.0 supposed to handle proxys that requires AD authentication?
To bypass the proxy is not an option
Setting a proxy exception for these servers is maybe an option
Prefered is that Acrobat handles this

Answer 1

To update my own question since it might help others
I received assistance through the Adobe support channels
Not what I was hoping for but it clarifies the problem
The reason I asked the question is that we don’t support Shared Review with an Authenticating Proxy server. So this customer workflow isn’t too far off the mark with having a proxy server authentication expectation in the standalone client and wanting a timestamp server time.   The only workaround to this behavior is to do exactly what they have found.  Launch an instance of Internet Explorer, authenticate against the proxy server and then sign the PDF file.