Ubuntu server distros for non pae thin-clients...
 

I have been using Ubuntu 10.04 alt-server as a thin-client server for a number of years now.
I've been experimenting to get a new installation of Ubuntu 12.04 to 16.04 with LTSP setup, using a usb but the thin-clients never boot !
The same message concerning '..using a kernel that's appropriate for your CPU. PXE: pae' keeps coming.

The server is a HP Proliant ML350 G4p with 3.0 Ghz CPU, with 250 GB HARD drive, running with 4GB RAM.
The thin-client model is: HP t5525, with a linux kernel, made in 2005.

I have tried the 'force-pae' options but that still doesn't work.

Any areas i need to work on? What have i not done right?
Or what else should I do?
Anyone.

Thanks.