I was working at a client migrating some MOSS 2007 servers from Windows 2003 to Windows 2008R2 and ran into an odd issue with a custom user control they were using for a Captcha. When you tried to access the control and its associated graphics in the _controltemplates library you would get a 403 Access Denied error. It was really odd. It seems that this is an IIS 6 to IIS 7 change and you have to update the IIS 7 system to allow it to execute the user controls. Here is how you do it.
- Open up IIS 7 on the machine.
- Select the _controltemplates virtual directory
- In the IIS section select the Handler Mappings feature and double click on it.
- You will see a log list of options and most will be greyed out. Scroll down until you see AboMapperCustom-#, highlight it and select Edit Feature Permissions
- On the next screen select Script and Execute and your user control should work.