mprexe errors when nic card is not conne

We have several clients on Toshiba laptops who are having trouble booting when their NIC cards are not connected to the network. I get an MPREXE not responding when I check for errors. Our quick fix so far is for the client to remove the NIC card when not logging on to the network. Would prefer to find a better solution. Currently using Client32 version 3.1.0.14