Updated on 32 bit system (x86) to V5.1. Program opened blank left hand side panel. Mouse pointer did not work on opening screen or the top toolbar except icon red box top right to close manually cleaned up the whole system of Libre Office Started again by downloading a previous version of V5 (V5.0.0.4 (x86)).
This appears to be an OpenGL blacklist issue. Remedy is announced for the versions to come.
If you want to use V5.1.0 nonetheless simply turn off the option ‘LibreOffice’ > ‘View’ > ‘Use OpenGL for all rendering’ in V 5.0. Installing V 5.1. on top will preserve the user profile containing this setting and anything should work nicely again.