Since you can ping resources by FQDN but not the single system name, it sounds like there is an issue with your clients not having their IP settings configured correctly to automatically append the appropriate domain names.
For example, if you ping PCTEST1, it should be configured to automatically ping PCTEST1.domainname.com.
For more information on configuring automatically appending domain names, please visit the following Microsoft Support article -
http://support.microsoft.com/kb/305553.
Hope this helps...
Mike