We'll start off with the facts that DP 6.1 has been out of support for several years, and you are in an unsupported configuration with DP 6.10 on windows 2013. Thi smay have nothing to do with your question, but, it is not helping
You should always start with some basic information
cd \Program Files\Omniback\bin
omnidbutil -info > info.txt
Look for teh ratio between Records Used vs Records Total in the Catalog section of the output. Anything smaller than 90% will indicate a very fragmented IDB, and could cause this problem
omnidbutil -extendinfo > extinfo.txt
Look to be sure that none of the Tablespaces are full to overflowing, if you see one or more where Current space is very close or equal to Maximum space, you need to create a new Tablespace, and, probably purge your IDB
omnidbcheck -extended
Run this when there is nothing else runing. Everything should come back as OK, if not, furthere action needs to be taken