You might try the steps given in the following links:
Let me know if it worked.
We have the same error message here. One of my co-workers cannot sign with her CAC.
A reboot just fixed it. Odd, but typical, right?
Actually, strangely enough one of my customers just had this problem pop up and before I had the chance to troubleshoot or research it, called me back with their perceived fix on this. They simply closed everything that was Adobe associated (meaning all Adobe programs and files that were opened) and then re-launched and assumed normal functionality. So a reboot of the entire machine may not be immediately necessary. But should be considered to reinitialize any background processes that might be time dependent/sensititve.