This is a new occurrence of an old problem. I can not use USB connected drives or memory sticks.
This just started yesterday after a software update. I ran my backup software the same as usual, but it crashed.(Lucky Backup)
In checking, I saw that my EXT4 external drive no longer had me as the owner. I have no idea how the ownership was changed. I had created the single backup directory on this drive about 6 weeks previously.
Since the files on this drive were simple duplicates of the files on my hard drive, I deleted the EXT4 partition and created a NTFS partition on the backup drive.
Once more I did a backup, and once more it crashed.
As a test, I tried to copy 20 GB of photos to a FAT32 memory stick with 32 GB of empty space. This also crashed.
I ran a memory test for an hour and found no errors.
Unsure of relevance, but the log shows continuous errors by LIRC.
Using Ubuntu Gnome 17.10.
This has also been posted on Facebook.