FTP chainloading a menu.ipxe

[NiKiZe]

san commands over FTP, probably to much of a nightmare.

Ok - so the actual error description that you should have in your opening post is: "when i chain over ftp, PC reboots"

When testing, I would use iPXE without embeded script.
add || shell at the end of your chain line - just to be sure that you get back to shell if it fails.

You might also want to use imgfetch instead of chain, followed by imgstat, to see that the script is detected correctly as an ipxe script and not a binary of some sort that it tries to run.
With that out of the way, my guess would be hardware issues, and I would start with running memtest to check for any issues with memory.