Hi and welcome.
I can see no reason why the LAN controller being disabled in the BIOS should have any effect on the USB3.0 ports.
Yea strange indeed. Would anyone be able to test this board and verify?
These flash card readers often seem to cause problems in one way or another. I don't know why it would do as you describe but I can't say I am surprised.
Still, it works fine on USB2 ports. I'll test other devices.
There have been a few teething troubles with the USB3.0 devices many of which are sorted out by a BIOS update. Are you overclocking anything at all ? Perhaps a little more information about your setup would help throw some light on things.
No overclocking. (The graphics card is OC version by manufecture but that should be fine)
CPU: i3 2120
Memory: 4GB (2x2GB) Corsair DDR3 XMS3 Classic, PC3-10666 (1333), Non-ECC Unbuffered, CAS 9-9-9-24, 1.50V
Video Card: MSI GTX 550Ti Cyclcone 2 OC
HD: WD 2.5' 320GB laptop drive
Case: Silverstone SG05B 450W
BIOS - comes with F5. I updated to F6e.