Ensure the VTSUser account has Supervisor rights in The Raiser's Edge.  

The password for this account may have been lost and needs to be reset.  Reset like normal through The Raiser's Edge and adjust in IIS:
  1. Start > Run > inetmgr
  2. Select the VTSWebUI application under Default Web Site
  3. Click "Application Settings"
  4. Update REPassword field to new password