Known to apply to the following Sophos product(s) and version(s)
Sophos UTM v9
Sophos UTM v8
Sophos UTM v7
V7, V8, V9
What To Do
To test the memory on your UTM for errors, memtest86 or memtest86+ are useful tools. First, download and burn a memtest iso:
http://www.memtest.org/ or http://www.memtest86.com/
Then, connect a monitor, keyboard, and USB CD-ROM (with the memtest CD inserted) to your UTM, and boot it up.
When the bootloader appears, choose to boot from the CD. Once booted, memtest will automatically load and begin testing your UTM's memory.
Example screenshot of defective memory: