My apologies for reviving an old thread but I recently experienced the same issue.
1. If you do not use any Plantronics devices (like earbuds or headsets) on your computer, uninstall Plantronics Hub and make sure that the folder C:\Program Files (x86)\Plantronics\Spokes3G (thanks to EricTT) is indeed removed.
2. If you use a Plantronics device and still need Plantronics Hub, just update to version 3.11 or greater (see also discussion in the Plantronics developer forum).