I am trying to sign a document using an IdenTrust token, which worked with Reader X, but after reader updated itself to DC it does not work. The dialog to select the certificate comes up as it normally would, but after continuing from there it does not ask for the password and simply goes into a Not Responding state. Even after leaving it as not responding for over 5 minutes it does not fix itself.
Per another post I tried renaming the Security folder and it did not help. It is also updated to the current version via the Help -> Update option.
We found that this was a user profile issue. We tried uninstalling, upgrading and running the cleanup utility from Adobe and reinstalling. We also uninstalled and deleted the user's AppData folders for Reader and reinstalled. The only fix was giving them a fresh profile on the computer. This happened in both XI and DC.