Hello Rambabu,
did you find a solution to your problem?
I have the same issue (imported custom webdynpro DCs from NWDI 7.01 into NWDS 7.31, and getting "unhandled event loop exception" for every view I open).
I also made the mistake of closing the workbench, and was not able to start NWDS again, but solved that by temporarily renaming directory workspace.jdi.
Thanks,
Christiaan