Where the heck did my pc vanish to.

I work in a large facility with several pc's hooked to the network. Each pc
has and IP allocated to it. They all are XP machines. I can ping the missing
PC from with in the building, So I Know it is still in the building some where. Note this is a dedicated network. The place has numerous switches throughout
the facility. I need to find at least what switch it is on so I can get a general
idea where to began looking. Switch and port would be very nice.
I have the IP address of the missing machine.

 

How can you misplace a PC?

 

I didn't misplace in. Someone barrowed it and didn't return it.

 

How is a PC usually gotten in your facility? Routine-wise if broken and needs replacement.
Is there a central office or person that has to be contacted?
Maybe someone requested ond and was denied or got tired of waiting.The person in charge of disbursment may know of something like that.