Login to new installation not working

Login to new installation not working

Hi Guys,
 
I have just configured a new ServiceDesk install as follows:
 
Windows 2008 R2
SQL Server 2008 R2
SDP 8.1
 
The installation completes fine and SDP starts up ok, however I can't login to it. When I try and login using either the "administrator" or "guest" accounts that it specifies on the login screen, I just get an error message as follows:
 
Username or Password is incorrect
 
I have opened the SQL Server management tools and can see the servicedesk database and everything seems to be pk, just SDP refuses to log me in with the defaults provided.