var
  reg:TRegistry;
  Path:string;
begin
  path:= 'Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU';
  reg:=TRegistry.Create; reg.RootKey:=HKEY_CURRENT_USER;
      reg.DeleteKey('Software\Microsoft\Windows\CurrentVersion\Explorer\RunMRU');

     SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST, NiL, NiL); //刷新

上面的代码还是不行,有没有朋友能帮忙啊

RunDll32.exe USER32.DLL,UpdatePerUserSystemParameters