Read the complete post at http://msmvps.com/blogs/tech-steps/archive/2009/11/12/the-report-server-web-service-is-unable-to-access-secure-information-in-the-report-server-please-verify-that-the-webserviceaccount-is-specified-correctly-in-the-report-server-config-file-rsaccessdeniedtosecuredata.aspx