If suddenly SAPGUI stops connecting to the all SAP servers with the error:
Service ‘sapdp00′ unknown
Method: NiPGetServByName2: service ‘sapdp00′ not found
Return code: -3
System Call: getservbyname_r
Usually this is caused by a registry problem. Regedit the following key:
The key DataBasePath should be of type "REG_EXPAND_SZ". If it’s not, the easiest workaround is to replace %SystemRoot% in the data of the key with C:\WINDOWS (or whatever %SystemRoot% is in your system).
If’ve read in a couple of forums that this change is usually caused by MSN Messenger.
P.S. 2006-05-02: A new SAPNote 882741 deals with this problem.