I have a pair of Monitor 10's looks like they were from 1987. The sound in one speaker is one quarter of the other - any ideas??

if any of the front speakers can be removed from the outside of the cabinet, you may be able to push the cabinet back off by going in the front.

The monitor driver is for your computer to recognize all the resolutions your monitor can handle, there is no sound driver for the monitor to work since the monitor built-in powered speakers are jsut that, powered speakers, same as the one you buy if the monitor does not have built-in powered speaker.
You can test the monitor speaker system by feeding it with the MP3 player or any sound sources.
It may have bad power amplifiers IC. You will be better off spending money on a good set of PC powered speaker system that will provide a lot better sound quality than the quarter-size speakers in the monitor.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm/

Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.
Or www.digikey.com just make sure to use caps with low ESR, 105c, high ripple current, long life rating such as PANASONIC FM or FC series.

Best to use the line out jacks. The phone jack is stereo and you would have to use a wye cable for that.

Lets find out first if it is the monitor' powered speakers problem or the sound card problem.
Try feeding the monitor with sound source such as MP3 player, if it does not work, then the power amp circuits may be at fault, it may not be worth having it fixed since you will be better off spending the money on a good set of powered speakers that will put out so much better sound than the speakers the size of a quarter in the monitor.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm/
Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Not likely, most speakers in the monitor are about the size of a quarter!
They are made to sound not better than an AM radio.
You will be better off getting Powered PC speaker set instead.

http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm
Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

You would need to connect the speakers to your computer. There should be a little jack on the back of the monitor marked audio. This will need to be connected to your soundcard jack for front speakers. Once this cable is connected you should have sound from your speakers. Hope this helps.

Static shock can fry your sound card from electro static discharge and it can also fry other PC components try another set of headphones in the pack of the PC. Or another pair of speakers rather than using your monitor and see what happens.

No Problem. I am here to help. Ok first you have to make sure that the speakers have cable that come out of them that looks like this http://www.allaboutsymbian.com/images/features/N95/photos/DSC03189.JPG

Then just plug it in into the green jack at the back of you monitor or PC. Hope it works.

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Is there actually any unknown devices in the device`manager?

Are your monitor speakers USB or do they plug into the audio out jack of your sound card or motherboard???

If they plug into the sound jack, then test the sound output with a pair of headphones.

Hope this helps you narrow it down. Please reply back if you need further help

sounds like interferance try moving the speakers around maybe away from the monitor and try turning off any thing elec around your pc to find out maybe what is causing this