Case Summary: If Webserver Parent Paths facility is disabled in IIS Version 6.X it will cause web+center to fail.
Web+Center 4.0 Production
MS recommends that on the webserver the Parent Paths facility should be switched off for additional security – please see technical article Q226474. This will cause web+center to fail so it should not be disabled. A possible work around might be to use an ASCII editor like textpad (from www.textpad.com) and use the search in complete directory features to do a global subsitution of the relative path includes and convert that to the fix path. This relative path is required for multiple installs on one machine.
To verify or enable the parents paths App option under IIS perform the following steps:
1. Open the Internet Services Manager in the Microsoft Management Console (MMC).
2. Right-click on your Default Web Site and select Properties.
3. Click the Home Directory tab.
4. Click the Configuration button.
5. Click the App Options tab.
6. Click to select the Enable Parent Paths checkbox.
7. Click the OK button until you return to the MMC.