The issue occurs because of incorrect settings in Internet Information Services (IIS) 6.0.

To resolve the issue, please do the following:

1. Create a new application pool.

        a. Open the IIS Manager.

        b. Expand the server tree, then click Application Pools.

        c. Click Action > New > Application Pool.

        d. On the Application pool ID field, type "SMEX".

        e. Click Use default settings for new application pool > OK.

        f. Under the Application Pool folder, right-click Officescan and then select Properties.

        g. Click Identity.

        h. On the Predefined dropdown list, select Local System.

        i. Click Apply > Yes > OK.

2. Set the Officescan Virtual Directory to use the new Application Pool.

        a. In IIS Manager, expand the Web Sites folder.

        b. Right-click SMEX and then click Properties.

        c. On the Home Directory tab, click Remove > Create.

        d. From the Application Pool dropdown list, select SMEX.

        e. Click Apply > OK.

        f. Restart the Worldwide Web Publishing Service.

        g. Go to the Properties of the OfficeScan Website.    

        h. Click Directory Security.

        i. Click Edit.

        j. Change the "IUSR_Username" to the administrator account.

        k. Tick the Enable anonymus access checkbox.

        l. Restart the Trend Micro Messaging Security Agent Master Service.