PXE Installing ESX 5.5

I'm trying to setup ESXi to install via PXE Boot but it's stopping after loading menu.c32.

Under my tftpboot directory, I created a subdirectory called "esxi55" and copied the contents of the ESXi install CD. I also added the pxelinux.0 file from the Sysutils 3 package. I created the tftpboot/esxi55/pxelinux.cfg directory and copied the isolinux.cfg file to pxelinux.cfg/default

In my dhcp configuration I added:

host esx-test {

    hardware ethernet 00:50:56:ba:1b:37;

    fixed-address 192.168.1.10;

    next-server 192.168.1.20;

    filename "esxi55/pxelinux.0";

}

From the TFTP server logs I can see the machine load menu.c32 but then it just appears to stop and not do anything.

Any suggestions as to what I've done wrong?

Thanks,

GTG