LibreOffice freezes on startup after windows restart

Normally we have permanently a LibreOffice spreadsheat document open on our PC’s (one PC with Windows Vista, the other PC with Windows 7).
At every Windows restart without proper closing of files (because of energy saving shutdown for instance or after an automatic Windows update) we risk LibreOffice to freeze at startup. With LibreOffice 5 only the LibreOffice banner is displayed.
With the Windows Task Manager we can see that the LibreOffice processes scalc.exe, soffice.exe and soffice.bin are active but doing nothing at all. When we try manually to open a document with LibreOffice, additional LibreOffice processes appear in Windows Task Manager, but nothing else happens. The only way to get out of this problem and to restart LibreOffice properly is by canceling all LibreOffice processes in Windows Task Manager.
This freezing problem existed already in several LibreOffice 4 versions, but still persists in all LibreOffice 5 versions.
Selecting or disselecting the option to load LibreOffice at Windows startup, makes no difference.