[dba-SQLServer]Connecting to the server

My Boss's pc is running windows 2000 SP3 (I found out today he is on 
this later SP).  The problem I found last night was that for some reason 
his pc is not able to identify the SqlServer Name, if I add it in a 
connection string it can't find it, however If I replace the name with 
an IP then it finds it w/o any problems.

Why would this suddenly happen (yes I know MS, but really why?)? more 
importantly how do I fix it?


-- 
-Francisco