Having the same exact problem. We have a multiple VLAN environment and have been using CloneDeploy for a while with no problems. (Thanks by the way, it's AWESOME!) Three days ago however, we started getting the same message:
PXE-T04: Access Violation
PXE-E36: Error received from TFTP server
PXE-M0F: Exiting PXE ROM

We are running the latest version 1.2.1 with all defaults. No firewall or ports blocked that I know of.