Unable to play videos - transcoder fails

I am new to Plex, running PMS on I am running PMS on a Windows 7 machine, but I have so far been unable to get any video media to play due to the “Conversion failed. The transcoder failed to start up” error. Upon examining the logs, I am seeing the following error:

Unexpected error configuring transcoder: boost::filesystem::unique_path: Object already exists

I have seen a similar error that is discussed in the KB, but this does not appear to be the issue with the crypto/RSA directory, as I have followed the steps to resolve that issue.

I have tried reinstalling PMS (also rolling back to a previous version), but the error persists for all video files.

Any suggestions? Logs are attached.