Are you seeing an error message of PXE-E74 bad or missing pxe menu and or prompt information? The issue appears when the boot menu sent from the PXE server is long enough to cause the information to be split into two option fields. In this case the client does not accept the information from both options, and you see the error. As a workaround you can configure your PXE server to shorten the length of the boot menu.
I looked at the BIOS updates page for the ThinkPad T410 and did not see any mention of a fix for PXE boot. The PXE code is in the BIOS, so you will want to watch for future BIOS upgrades.
As a last resort, if you cannot trim your PXE boot menu, I found one discussion where someone resolved this issue by downgrading the BIOS. However, if you downgrade you might run into other problems. Shortening the PXE boot menu seems like a much safer choice.