If you have W5 pinned to your taskbar, this will inhibit the W5 update process from working correctly. This happens because when you pin W5 to the taskbar, you are pinning that specific version. When W5 updates, it downloads a new version of W5. By keeping W5 pinned, you are keeping the old version pinned, which is why W5 continues to update again and again.
The solution is to unpin W5, then run W5 from the desktop or Start menu shortcut, then let W5 update if it has not already, then run W5 and pin again if desired.
Update: As of W5 Claim Version 5.3, this issue will no longer occur.