If you are booting to WinPE 2 you need to use Vista 32 bit drivers. Adding every driver in the Lenovo catalog can also cause problems as, for example, there are several Broadcom drivers but not all Broadcom drivers work with every Broadcom chipset.
So you need to check the PNP ID of the NIC in each of your machines and make sure the INF file in the driver you are adding, includes that PNP ID in the list of supported hardware.
Try removing any drivers that are not relevant to the machines in question to avoid any chance that another older driver supports the same PNP ID and loads first.