A quick note in the hope that it may save somebody else a little time, stress and trouble.
If you're a LibreOffice user, and you run it under one or other GNU/Linux distribution, and you use the Nvidia Graphics Drivers (rather than some default generic driver), you might be tempted to enable OpenGL rendering for LibreOffice.
DON'T DO THIS.
For reasons that remain largely occult to me, this particular combination of circumstances causes LibreOffice to crash during startup. (For the C/C++ programmer who might care: It seems that there is a method pointer in the Nvidia driver that is null, so when LibreOffice calls this method during startup,... crashity, crashity, segfault, whump.)
The solution is simple: don't enable OpenGL rendering in LibreOffice. The option is there in among the LibreOffice options: Tools >> Options >> View >> Graphics Output >> Use OpenGL. Leave it well alone.
But what if you have already done that and your LibreOffice instance now refuses to run?
I guess there is some configuration file among LibreOffice's many (to be found in $HOME/.config/libreoffice and depths below) that would allow one to delve in with one's favourite text-editor (i.e. anything but nano) and fix it. I could not find it. In the end I simply removed the entire LibreOffice configuration tree and let it create a new one on the next startup (which was entirely and predictably successful, don'cherknow). After all, I tend to keep customisation as lightweight as I can, so it only takes a couple of minutes to put things back the way I like them, and not much harm done. It takes a fair while to discover all this, though...
Hope this helps someone out there. If you found a better way to fix this issue, I'd love to hear about it!
BTW: This seems to be quite independent of Linux distribution. The most help I found in searching for a fix came from the Mint and Arch communities. I use Kubuntu.