Buzzing LCD backlight inverter LG W2242T

Following on from my original homebrewed PC topic here: http://www.tomshardware.com/forum/261246-31-bird-beak-blessed-budget-built

Short version:
Does your LCD monitor buzz when below maximum brightness? What solutions do you know of - and how can you prove it to a technician?

Full version:
So the new PC is here and I've been working on installing bits and pieces on it all day, struggling with IE7 crashing after installation (it was annoying because I had to uninstall it before I could get Firefox). A few minor differences from the shopping list because of stock not being updated... and I got it at a different store than intended, for being closer.

Thing is, they didn't have the 19" monitor I wanted in stock, so I got a more expensive 22" version. It would be quite pleasing, if it wasn't for the fact that if lowered below 100% brightness at all - even to 99%! - it starts BUZZING near the power supply. A high pitched whine. Crackling, almost.

100% is insanely bright, and I shouldn't have to fiddle with videocard drivers to lower values to make up for it every time the ambient light changes. Besides, I live in Melbourne - we have four seasons in every day!

The monitor is an LG W2242T. I've read online that the issue can be caused by a faulty Backlight Inverter, or power supply, or a bundle of other stuff.

I'll be trying to get a refund from the store meanwhile, or credit... or anything. Hopefully it'll work out.

Of course, it's easy for technicians in a noisy room to say "It's not there! It doesn't matter! Get over it!" and be unhelpful - especially at MSY, a seller notorious for 'customer service'... so I'm here for any advice anyone can spare.

Thankee.