Issues related to Project Management JAVA API applications - Claim Digger, Update Baselines and XML Import/Export - are not easy to troubleshoot. I suggest you to open a service request at Oracle Support ASAP.
Generally speaking, causes are related to database connection settings (admin config table, internal plugins configuration, oracle or MSSQL configuration services) . Also you need to service pack your installation specially if you are using P5. Last SP is SP7. Meanwhile i suggest you to capture full event description (Clic on More...) and update baseline log file. Hope it helps.