HP ZBook15 stalling after a few minutes

[Izbi]

For some reason my ZBook15 stalls for about 30-60 seconds, each time I start the system, and it occurs about 5-10 minutes after booting. It occurs every time without fail.

Could it have anything to do with the following:

I reinstalled Windows but for some reason had to delete the 2 or 3 smaller partitions, I forget their names, one of them was "HP Tools" I think.

This may be off-topic, I don't know.

[iMaxx]

Which genereation of Zbook 15 do you have?
Does Task Manager show high CPU/RAM usage? Which apps?

Generally, slow downs are caused by software, with the possiblity of a bad hard drive.

Our recovery media and factory images create the additional partitions.

Have you tried upgrading to Windows 10?

[Izbi]

Task Manager does not show high usage. Cannot investigate during this problem though as everything freezes.

Hard drive was inspected with CrystalDiskInfo, result is "Good".

Do not want to upgrade to Windows 10.

With respect to "Our recovery media and factory images create the additional partitions": I did reinstall Windows from the factory CD. I had to delete the existing 2 or 3 small partitions because it wouldn't let me progress. What is specifically the "recovery media"? Is there a link to the instructions?

Kind regards.