glitch opening PDF files in Writer

All of a sudden I cannot open PDF files in LO Writer. Whenever I try to do so, I get this message: “General Error: General input/output error”. I have never had a problem of this kind before. I am using Writer v. under an up-to-date Linux Mint 18.3 Mate. My hardware setup is:
End PC Noise custom AMD Fusion Media PC
AMD A8-3850 2.9GHz quad-core CPU
4GB Kingston PC3 RAM
2 Intel 520 series 120GB SATA III SSD
Lenovo 24” pivot monitor, normally used in portrait mode
Northgate Omnikey Ultra keyboard
Shutting down and rebooting does not solve the problem.