send a copy of the metadata log file to support and ask them to take a look. They are best placed to answer these types of questions
thanks for your advice,
where is the location of metadata manager log file?
a quick search of the community shows this article which should get you started
I'd also look at the LDSDsetup.pdf file for 7.5 as this file is described here too
I'd also recommend you upgrade to 762 if you can as that is the latest version and more likely to get fixes applied than 7.5