The certificate enrollment process via Microsoft IE browser uses ActiveX controls to streamline and automate functions in the certificate lifecycle. On the Windows XP SP2 operation system, the required ActiveX controls MAY need to be installed manually by your IT administrator who has the administrator privileges to complete the installation. The following release notes provide the instructions for the various installation options and procedures for the required ActiveX controls which are packaged in the included VeriSign OnSiteMSI.msi file.

Under most circumstances, certificate enrollees with administrator privileges on XP SP2 operating systems should be able to install the required ActiveX controls by clicking through the ActiveX control download prompt within the Microsoft IE browser's Information Bar. However, if an error still occurs, please follow the instructions in the PDF document to install the VeriSign OnSiteMSI.msi package explicitly.  

Download: Update for Managed PKI on Windows XP SP2 Release Notes and OnSiteMSI.msi File