Go to Control Panel -> Administrative Tools -> Internet Information Services
Next, select Local comupter "Web Site" -> "Default Web Site" -> "ReleaseManager"
Then under the "directory security" tab click the "Edit" under "anonymous access and authentication control".
Uncheck the checkbox "Allow IIS to control password."
Then put the IUSR_<MachineName> into the Administrators group as a test.
Run IISReset. If you can now run the Release Manager application then either your IUSR_<MachineName> password was incorrect or that account doesn't have enough rights.