I understand that you are experiencing problems entering BIOS when you have a USB card reader connected to the motherboard.
In regards to your inquire, some USB devices may prevent other device to be properly recognized on your specific case I recommend you to use the back to BIOS button on the rear of the motherboard, pressing it will make your motherboard go in BIOS on the next boot. Another option will be to disable the boot from the USB device in BIOS, under the boot tab.
Hi PV, the problem still occurrs with usb boot disabled, in fact all boot options ex. cdrom and hdd are disabled.
It's not a big issue, I only mention it as it may be another piece in the puzzle of the other boot/hang issues. They may all have something in common.