You will need to provide some additional detail about your setup.
Version of CRM?
Is IDF and/or ADFS setup?
Some basic things to check:
From the client computer, does a nslookup of the CRM server name resolve? If not, it may be a DNS issue.
Is the CRM site in IIS listening to all IP addresses? Or set to listen to only one?
Was a host header set up in IIS for the CRM site?
What error do you get when you use the CRM server name from the client machine? Only IP addresses working is a sign of a kerberos issue. Check that you have the correct SPN's created for a non machine account running the CRM app pool in IIS.
Jason Peterson