I suggest you to go to Start to type cmd and to open the utility using Administrator rights. Type cd %windir%\system 32 in the command prompt, press Enter, type regsvr32 vbscript.dll, press again Enter, type regsvr32 jscript.dll and then Enter. After you receive DllRegisterServer in vbscript.dll succeeded message, run the Bing HRS Toolbar installer using Run as Administrator option.
If this doesn't work, perform a scan using System File Checker tool and try to install the toolbar using Administrator rights.