PC with WinXP-Pro acting as DCHP server unintentionally?

I have recently been experiencing problems when I plug my home laptop into my workplace LAN. My computer seems to be acting as a DHCP server (when it’s obviously not supposed to be,) thus creating network conflicts. I am running XP-Pro, and have internet connection sharing turned off. I am physically connecting to the LAN via a switch (not a router) and am only experiencing conflicts sporadically. I am stumped as to why my PC is acting this way. Help?