I tried pretty much the same method as Droront except I shut down steam, removed playonline and tetra master folders then opened steam back up and right clicked on ffxi~clicked properties~then Local files~finally Verify Integrity of game cache. Once completed this did force playonline viewer to update to latest version.

This in turn led to another problem; I now receive the message:
"The feature you are trying to use is on a network resource that is unavailable.
Click ok to try again , or enter an alternative path to a folder containing the installation package 'Playonline Viewer Tetra Master.msi' in the box below." The file is not present anywhere and I have no hard copy of the game.

Please help!