Mapped Network Drives and Offline Folders do not Appear on Server 2003 without Computer Browser Service?

Network Drives do not show up without Computer Browser Service to a particular Windows 2003 Server which also hosts Exchange, but Exchange/ping do work.  When computer browser service is started the network drives and offline sync for my documents do work, but not without this service which will not start at start-up.  Only a problem on 2 Dell Latitude d520 laptop's, not a problem on other Dell PC's including other Latitudes.  As soon as I go to Services.msc from run command and start Computer Browser Service, the network drives appear shortly there after and files are able to be synched.  Again, only a problem on 2 clients.  It was working fine on 2 previous laptops.  You can ping the server all day long so there is connectivity and the mapped drives to other servers do work.  This particular server is 2003 Server with Exchange and also hosts users my documents and desktop which are set for offline sync.  Other shares on this server can not be accessed without computer browser service.  I thought this was only needed for 98/NT legacy, etc.  We have a 2000 Active Directory Domain.  Help.