These are the known issue in Windows 10 PC preview build 14251

Microsoft has posted its list of known issues in its latest PC preview build of Windows 10, build 14251. Windows Insiders on the Fast ring that downlad this version may encounter the following issues.

  • You might see a WSClient.dll error dialog after logging in. We're working on a fix for this but as a workaround, you can run the following in Command Prompt with administrative rights: schtasks /delete /TN "\Microsoft\Windows\WS\WSRefreshBannedAppsListTask" /F
  • The Connect button does not show up in Action Center. The workaround is to press Windows key + P and then click "Connect to a wireless display".
  • Due to a recent memory management change, you may see periodic app crashes or other memory related app errors. The workaround is to reboot your PC.

An issue from the previous preview build that caused PC games to crash has been corrected.

Source: Microsoft