In IIS right click your website >select properties>
1.Go to the Directory Security tab for the site and click the Edit button under Anonymous access and authentication.Check the enable anonymous access.
http://forums.iis.net/t/1146459.aspxOr right click the folder under which the both files resides then go to security tab allow IUSR_MACHINE read permission (Inherited)
You can also run process pointer to check which on file the process is locked due to invalid ACL.