This is something i noticed with Bios A18 as well.  When i upgrade to A19, the com1 port on my E-Port Plus disappears - it's not listed as unknown device, nor does it appear like a device that cannot start or doesn't have the correct driver.  As soon as i downgrade to Bios A15, it appears again.

 

This is actually critical for my job, where I end up spending a lot of time configuring network equipment, and i do not want my usb to com adapter to go missing.