Original answer by Labnuke99 that seems to have been somehow overwritten
Stopping the DHCP client service by itself should not disconnect your device from the network. However, if that person’s login has the appropriate authority through their user credentials (local or domain administrator) they could easily shutdown any or all services on your computer. DHCP is used to request/register IP addresses for client devices. A device typically keeps its assigned IP address until it is powered off or the lease has completely expired.
I don’t know if you might have been doing some type of non-business activity to warrant whatever this other person <b>might</b> have done to break your network access. I would suggest that you ask them what they were doing on the network to possibly create the issues you are describing. I would also recommend having someone from IT with you during the conversation to help understand what is being said.
You don’t give any specific details about your network, so I have to assume it’s a corporate setting. If so, someone who has access to the servers on your network could execute remote commands, in this case the command “sc stop DHCP.”
This could also indicate someone trying to take advantage of a known vulnerability in the DHCP Client Service, that’s detailed in CVE-2006-2372 “Vulnerability in DHCP Client Service Could Allow Remote Code Execution (MS06-036).” The giveaway is that you say it was done by another user on your network. The vulnerability requires that: “For an attack to be successful the attacker must send the affected host a specially crafted DHCP response communication from the same network subnet.”
You should immediately download and apply the patch to your system; the various versions are listed in the article linked to above.
You can not simply disable DHCP Client service even if you assign a static address because dhcp client service is used also for registering dns name regardless is it static or dynamic addressing in place.
Hope this helps.
You can keep up with various security issues at Security Corner.