What could be the reasons for disabling the port in protection on the switch?

Question

network hardware

I work as a fitter for a provider and periodically problems began to appear in a disconnected port on the switch (it seems that this did not happen before), concurrently I take a PC from people for repair and I haven’t quite decided on such ports.
1. I installed a PCI card and everything worked.
2. Reinstalled the system and it worked (reinstalling the drivers did not help).
What could be the reasons for this behaviour? Can you do without such cardinal decisions?
The port on the switch turns on literally for a second when turned on in a faulty PC and turns off for the next few minutes.

Answer 1

for example, people have a dhcp server up. in this case the port is cut off due to dhcp spoofing.

Answer 2

Stop doing nonsense and treat the problem, not the consequence.
The reason for blocking the port in English on black is written in the switch log. This is for your admins. And you are minding your own business. Let the admins set you a task with a description of what actually broke something.