The resource cannot be found - /Account/LogOn

Using

• IdB service v4.1.5.5
• IdB for Microsoft Active Directory 4.1.2.1
• IdB for PeopleSoft Connector 4.1.0.0
• IdB for FIM 4.0.0.3

* Note - About page incorrectly showing this: "UNIFY Identity Broker Management Studio, v0.0.5 Revision #5" ... can't explain this!

The following error is thrown when starting on the ABOUNT page (/About) and clicking on the Identity Btroker home page image to return to the dashboard.

The resource cannot be found. 
  Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable.  Please review the following URL and make sure that it is spelled correctly. 

 Requested URL: /Account/LogOn

The URL for this page is as follows:

http://localhost:8008/Account/LogOn?ReturnUrl=%2f

I am running IdB under IIS.  Navigating directly to the home page (by removing everything after the 8008 port number in the URL) also fails - only works after I put in a trailing ?, i.e.

http://localhost:8008/?

I am using a clean install of IdB 4.1, using the extensibility files from the (to be retired) existing v4.1.4 RTM version.