Hello Andy. Do you have any error logs being generated by SmarterStats in and around the time you last tried to log on? Those logs can be found in:
C:\Program Files (x86)\SmarterTools\SmarterStats\MRS\App_Data\Logs
Also, if you log on as the system administrator can you impersonate the site from there, or does this fail as well?
Kyle Kerst
Acting IT Manager
SmarterTools Inc.
www.smartertools.com