Optiplex 755

These 755's PXE boot just fine, get an address and connect to the imaging server and display the img menu, but once the kernel loads they lose the network and can't talk to the server anymore. I've tried boot files from ir3a, ir3a img resource file, and the sles10sp2 patch, with and without the newid setting in the cmd file. From everything I've read here and on support these files should be working. Any idea what I could be missing?