Wsus installation time i got error

Hi!

i have new windows 2003 standard edition with SP2 server i have install IIS v.6, Asp.net 2.0.50727
and microsoft report viewer but when i install WSUS 3.0 i get this error in log file.

pls. help me

error

2007-08-05 08:44:08  Success   MWUSSetup          Validating pre-requisites...
2007-08-05 08:44:09  Error     MWUSSetup          Failed to determine if an higher version of WSUS is installed. Assuming it is not... (Error 0x80070002: The system cannot find the file specified.)
2007-08-05 08:44:26  Success   MWUSSetup          Initializing installation details
2007-08-05 08:44:26  Success   MWUSSetup          Installing ASP.Net
2007-08-05 08:45:05  Success   MWUSSetup          ASP.Net is installed successfully
2007-08-05 08:45:05  Success   MWUSSetup          wYukon is already installed on this machine
2007-08-05 08:45:05  Success   MWUSSetup          Installing WSUS...
2007-08-05 08:45:10  Success   CustomActions.Dll  Successfully set propery of WSUS admin groups' full names
2007-08-05 08:45:10  Success   CustomActions.Dll  .Net framework path: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727
2007-08-05 08:45:12  Success   CustomActions.Dll  Creating user group: WSUS Reporters with Description: WSUS Administrators who can only run reports on the Windows Server Update Services server.
2007-08-05 08:45:12  Success   CustomActions.Dll  Creating WSUS Reporters user group
2007-08-05 08:45:12  Success   CustomActions.Dll  WSUS Reporters user group already exists
2007-08-05 08:45:12  Success   CustomActions.Dll  Successfully created WSUS Reporters user group
2007-08-05 08:45:12  Success   CustomActions.Dll  Creating user group: WSUS Administrators with Description: WSUS Administrators can administer the Windows Server Update Services server.
2007-08-05 08:45:12  Success   CustomActions.Dll  Creating WSUS Administrators user group
2007-08-05 08:45:12  Success   CustomActions.Dll  WSUS Administrators user group already exists
2007-08-05 08:45:12  Success   CustomActions.Dll  Successfully created WSUS Administrators user group
2007-08-05 08:45:12  Success   CustomActions.Dll  Successfully created WSUS user groups
2007-08-05 08:46:29  Error     MWUSSetup          InstallWsus: MWUS Installation Failed (Error 0x80070643: Fatal error during installation.)
2007-08-05 08:46:29  Error     MWUSSetup          CInstallDriver::PerformSetup: WSUS installation failed (Error 0x80070643: Fatal error during installation.)
2007-08-05 08:46:29  Error     MWUSSetup          CSetupDriver::LaunchSetup: Setup failed (Error 0x80070643: Fatal error during installation.)
2007-08-05 08:46:57  Error     MWUSSetup          DoInstall: Wsus setup failed (Error 0x80070643: Fatal error during installation.)