Error Getting License: Server communication problem: E_ADEPT_INTERNAL

Attempting to download several files from Direct2Drive.com. I've already contacted their tech support about this error. Their response:

"I've tested the download server links and we're seeing that the downloads have been fulfilled and activated by your computer. Can you try removing the digital editions software from your computer, then redownload Digital Editions. If the downloads still do not operate, please let me know, along with  contacting Adobe for assistance with this as our servers would not appear to be at fault."

As suggested, I have uninstalled Digital Editions and then reinstalled it. No change; I'm still getting the exact same error message ("Server communication problem: E_ADEPT_INTERNAL").

Any suggestions, please?