Don't know about microphone problem ( I presume that's what you mean by audio glitch), but USB HHD's that weren't recognized by BIOS A05 are happily recognized by A06. That alone is worth reflashing for me.
I'm a noob. How do I flash my bios?I am afraid of damaging the computer in the process if I do it wrong. Is it difficult to do?
Dell made it very very simple. You download .exe file and double-click on it. Make sure your battery is fully charged and your AC is in. The only bad thing that can happen is your lappy losing power during flash process.