“Access Denied” using Trend Micro Officescan 5.58?

A client uses Trend Micro Officescan 5.58. On Windows Server 2000, this works fine, but on Server 2003 it goes awry. Install does not pose any trouble, but after installation, there was no way for me to log into the Officescan’s control panel. The result was a 403 Forbidden: Access Denied error while calling up http://server/officescan/cgi/cgiChkMasterPwd.exe.

A day later, the client came up with the solution: switch on IIS 5.0 isolation mode in Windows Server 2003’s IIS 6.0: