Can't access to BIOS if FAT32 USB-drive connected

I have a weird problem with my ASUS N56VJ laptop.

I wanted to try some live Linux-distros from USB, but noticed that If my USB-drive is formatted to FAT32, I can't access to BIOS. The F12 button does nothing.

If I format the drive to NTFS, I can get to the BIOS normally.

Second weird thing is that I can't select "Quit without saving". The screen just flashes and does not exit from BIOS. I can't enter to Easyflash utility either...

My BIOS information:

Model   American Megatrends Inc.
Version N56VJ.203
Date    29.8.2012

I also checked the asus website and reinstalled the same bios version because there was no newer version.