I set my N9 to automatically connect via USB in mass storage mode using Status Menu Extension. I then tinkered with N9 QuickTweak settings and rebooted. Now my phone is in a reboot loop.

I tried to flash the phone to solve the problem, but because I had set it to mass storage mode, whenever I connect the phone to the computer, it fails to recognize the phone stating that drivers could not be installed.

What do I need to do to have my computer recognize the phone to be able to flash?

That's strange, I would imagine that regardless whatever the default operational USB mode is the device would always enter flashing mode when it is powered off and you connect it to computer where you have flasher polling for a device.

Are you sure you had the device in POWEROFF state when you tried connecting it to computer?

you need to power off by holding power button for 8-10 seconds then instead of flashing fix the issue using rd-mode...

the wiki for n9qtweak has it: http://wiki.maemo.org/N9QTweak#RD_Mode

It is powered off when I connect.

I run the flashing command after which I have a line stating "No suitable USB interface found, waiting." I then connect my phone to the computer and get a notification from Windows that a new hardware has been found. Windows tries to install the drivers, but after a while displays two red crosses with a caption "device unplugged."

I'll try to run the rd-mode and see what happens.

Install the drivers beforehand so its easier...Get them from my db: http://db.tt/iilwoJ1o

Thanks!

Rd-mode worked. Booted the phone up, started N9 QuickTweak, run command Z for complete restore, and my N9 is working properly now.

This is just one of the reasons I don't use windows, well for anything, really