Some process is using one or more files (dll's). It may be Domino or AntiVirus or something.
Maybe this thread can help:
http://www-10.lotus.com/ldd/nd6forum.nsf/55c38d716d632d9b8525689b005ba1c0/a946f403ec0bc8ae85256d5800131860?OpenDocument
Else you can search this forum for '-115'
Good luck