Cannot Login to Project Server - HRESULT 5011 on LgnIntAu.asp

[Paul Galbraith]

I get a 5011 result code when trying to login (programmatically) to project
server using the LgnIntAu.asp page...the login process is fine when I just
point my browser there directly, does anyone know where I can find out what
the 5011 HRESULT code means?