Hi,
It seems to be an issue with either the IUSR account or IIS. Check for the logs in the event viewer and let us know if there are any related to the same. In the meanwhile you can try the following as well however please do remember to take a proper backup of your database. (
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007082112135948)
Check the IUSR account
The IUSR account should be a member of Guest groups.
Check the
--> Properties of Symantec Web Server
--> Directory Security tab
--> Edit under Authentication and Access Control
--> Add the IUSR account and password
Restart the IISAdmin services and SEPM Service.
Try to login to SEPM Console
In case this ddoes not help then after taking a proper backup as mentioned in
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007082112135948 and then reinstall IIS and SEPM.