I also saw this symptom of the agent disabling the DHCP service on client machines after an image was deployed. I found that if you are willing to wait long enough (and I mean along time, maybe 45 minutes) it will eventually come good and carry on with the config task. As an alternative, I also found that if I manually re-enabled and started the DHCP service, that would move things along. On the same machines, I also had a weird 17 minute delay after every reboot before the client would communicate with the console (all other communication was normal, no issues browsing local network resources etc etc).
As for drivers, I was using the same PXE/PreOS for Win7 and Win10 builds on the same machines...Win10 is just fine thanks so it can't be drivers.
I did NOT find the cause as such, but the cure for those particular issues was to start a fresh Win7 install on the machines baed on the product recovery disks, rather than using the as-supplied fresh from HP Win7 install complete with bloatware.
FWIW, I never got a single response as to why the agent messes with DHCP like that when the job is defined for DHCP. I didn't bother trying it out with a manually defined IP address, but that might be worth trying??
My world of GSS3 pain has centred around HP450G3 laptops with SSDs. These thigns really DO NOT get along with Win7/GSS3.x I'm still struggling now with what feels like random problems cropping up every time I think I've got it gripped.
Good luck finding a resolution.