Some users have experienced a repeating authentication popup when attempting to connect to the comment server when viewing documents. The issue has been isolated to old adobe reader registry keys. The following instructions describe how to delete the old registry keys.
If you're not familiar with modifying the registry, we recommend that you ask an IT professional to help you.
Deleting the wrong keys in your registry can cause serious problems.
Click on the windows start button and type 'regedit' (without quotes) into the run/search box and hit enter.
When the registry editor opens up, expand the following path(s).
For Reader 11
HKEY_CURRENT_USER > Software > Adobe > Adobe Synchronizer > 11.0 > Credentials
For Reader 10
HKEY_CURRENT_USER > Software > Adobe > Adobe Synchronizer > 10.0 > Credentials
For Reader 9
HKEY_CURRENT_USER > Software > Adobe > Adobe Synchronizer > 9.0 > Credentials
After clicking on the Credentials folder, you should see several lines (keys) in the right pane. you will want to delete all keys except for the default one. Hold CTRL while clicking each key (except for the default) and once they are all highlighted in blue press the delete key on your keyboard. Then click yes to the confirmation.
If you have several versions of adobe synchronizer installed, you should repeat this process for each version (11.0, 10.0, 9.0).
Once you've deleted your credential registry keys you can close the registry editor and try viewing your document again. You will need to re-enter your username and password for each domain that you've connected to in the past. Once you've entered your login information for each domain, you shouldn't be asked to rekey your information anymore.
Please contact support if the problem persists.