*Error: Application cannot be Started. Contact the application vendor.

The Booking Agent uses Microsoft's ClickOnce technology to install and update the application.

The is a reported problem which can cause unstability.

To repair the problem:

1. Click Start > Control Panel > Add / Remove Program.
2. Select Booking Agent.
3. Click Remove and follow removal instructions.
4. Re-install the application and re-register the company.
   https://officedoxs.zendesk.com/forums/78133/entries/68905

Reference:
http://msdn.microsoft.com/en-us/library/ms229001.aspx