Lost connection to Requirements Management server in next generation DOORS (?log4j:ERROR)

I have been successfully using a trial license of DOORS Next Generation 5.0.1 on a locally installed Derby database / Tomcat server for the last few days. However, today I have not been able to access the data repository for the Requirements Management module only. Unfortunately, this is where all my data is. I performed a default install which, up until now, has logged me in rm, qm and ccm simultaneously.

The dropdown menu from the home button states that the Requirement Management server is offline or unavailable. There is also a login button for rm on my Dashboard but this does nothing (the qm and ccm are automatically logged in).

Since the problem started yesterday, I have been getting the errors below in the rm server error log. In each case they were followed by a long list of locations and causes, which appear to be the same for each error (although I have not checked exhaustively). Could these cause what I have been seeing? Or would you need more data on the errors to establish the cause?

2014-11-21 09:29:18,970 [          http-bio-9443-exec-8] ERROR ronting.server.services.adminhome.AdminHomeService  - CRRRS1007E  A problem occurred in the Requirements Management (RM) server: Entry [88ab3b307def9922]

java.lang.RuntimeException: com.ibm.team.repository.service.compatibility.util.http.CrossServerHttpClient$RestCommunicationException

2014-11-21 09:29:24,617 [          http-bio-9443-exec-2] ERROR server.services.discovery.OslcDiscoveryRestService  - CRRRS1007E  A problem occurred in the Requirements Management (RM) server: Entry [9c8e6f976b80ac1e]

java.lang.RuntimeException: com.ibm.team.repository.service.compatibility.util.http.CrossServerHttpClient$RestCommunicationException

2014-11-21 09:29:27,331 [         http-bio-9443-exec-14] ERROR server.services.discovery.OslcDiscoveryRestService  - CRRRS1007E  A problem occurred in the Requirements Management (RM) server: Entry [90eded2ee37e82ee]

java.lang.RuntimeException: com.ibm.team.repository.service.compatibility.util.http.CrossServerHttpClient$RestCommunicationException

2014-11-21 09:29:30,124 [         http-bio-9443-exec-28] ERROR server.services.discovery.OslcDiscoveryRestService  - CRRRS1007E  A problem occurred in the Requirements Management (RM) server: Entry [63405433e4e8c5ea]

java.lang.RuntimeException: com.ibm.team.repository.service.compatibility.util.http.CrossServerHttpClient$RestCommunicationException

2014-11-21 09:29:30,841 [         http-bio-9443-exec-18] ERROR server.services.discovery.OslcDiscoveryRestService  - CRRRS1007E  A problem occurred in the Requirements Management (RM) server: Entry [28021e2e66a282b0]

java.lang.RuntimeException: com.ibm.team.repository.service.compatibility.util.http.CrossServerHttpClient$RestCommunicationException

2014-11-21 09:29:31,075 [         http-bio-9443-exec-20] ERROR server.services.discovery.OslcDiscoveryRestService  - CRRRS1007E  A problem occurred in the Requirements Management (RM) server: Entry [ff91dbf3592beaf]

java.lang.RuntimeException: com.ibm.team.repository.service.compatibility.util.http.CrossServerHttpClient$RestCommunicationException

2014-11-21 09:29:31,231 [         http-bio-9443-exec-21] ERROR server.services.discovery.OslcDiscoveryRestService  - CRRRS1007E  A problem occurred in the Requirements Management (RM) server: Entry [d25a624b8dc74377]

java.lang.RuntimeException: com.ibm.team.repository.service.compatibility.util.http.CrossServerHttpClient$RestCommunicationException

2014-11-21 09:29:31,777 [rm: AsynchronousTaskRunner-4 @@ 09:29] ERROR com.ibm.team.repository                             - CRJAZ2388E The background process that synchronizes user data between servers could not be completed. The synchronizer will attempt the synchronization again.

CRJAZ1166I The stack trace hash is 4E9D01E287608D1FBC17887955D48BF08F866F41.

com.ibm.team.repository.service.compatibility.util.http.CrossServerHttpClient$RestCommunicationException: Forbidden

I hope you can help. Many thanks.