Error while opening message mapping in NWDS

Dear Experts,

I am getting error in NWDS when i try to open/create a message mapping. The error description is Unable to create editor ID com.sap.ide.esr.tools.messagemapping.editor: An unexpected exception was thrown.

Now my ESR SP level as per System information-->Components info is PI 7.3.1 SP 8 PAT0.

My NWDS version is

SAP Enhancement Package 1 for SAP NetWeaver Developer Studio 7.3 SP08 PAT0000.

Also, what does the version level in ESR-->Help--> About Enterprise Service Builder signify? Because that gives me an SP 01 NW731EXT_01_REL.

Regards

Varun