I've got a Logitech USB headset, and a Logitech QuickCam webcam. These devices only seem to work in the front left USB port in my computer.

When the headset is plugged into any other port, the audio becomes terribly distorted.
When the camera is plugged into any other port, the camera returns a black screen.

Tried un/reinstalling the software for the webcam, tried uninstalling the headset, tried uninstalling all of the USB ports.

Just seemed to happen out of the blue, and I'm getting fed up with it. Any help?

Do the USB ports all work fine with other stuff, like printers or memory sticks?

Yes.

My only idea is that maybe your PSU is at its limit, and only those sockets get enough power for the devices.

I once had a friend whose computer would turn off if he plugged a printer into a certain USB port for that exact reason.

Nah, this used to work fine before.

And...more things are going bad. Headphones refuse to work in either of my front USB ports, and scanner had to have its plug switched to function.

:/

Then it's probably drivers, either for the ports or for the headphones.

USB drivers most likely.

Any way to get those sans uninstalling/reinstalling every USB port?

I find it funny ...that you always say divers, but from what i read, "front usb ports" So the front usb ports on his computer are most likely pluged into the motherbored. and the one usb port that is not working right may be lose on the plugins / not grounded right.

He claims that's the only one working right for these devices though.

Went into my computer's insides and checked all of the cabling, all seemed plugged in, unplugged/replugged some power cords and cleaned the whole thing out.

Now the problem has switched; the devices only work in the RIGHT front USB port.

:////

Problem persists.

I don't know if this will help you, but I had a similar problem. My camera worked fine for video, but whenever I connected audio input it would start getting bad interference similar to feedback.
All I had to do to fix it was go into windows sound and audio properties and do the hardware test under the "Voice" tab. I don't know why it fixed it, but it did.
EDIT: Nvm, it still fails miserably.