"Unknown problem somewhere in the system." is a generic error. You get it when ever anything containing "Error or Failed" is written to one of your monitored logs. You can see the error in the a rules file. I'm not near my system now can't give location. If you add a new custom rule to deal with "HDIO_GET_IDENTITY" it will remove the unknown problem error message you received.
Your 'error" is Linux related. Does it happen when you mount the USB drive? Try changing your SeLinux mode and also examining your mount options. The following seems relevant: https://bbs.archlinux.org/viewtopic.php?pid=1015693 https://bugzilla.redhat.com/show_bug.cgi?id=759783
