Microphone output ridiculously low, unhearable

I am about ready to pull my hair out here.
This has been an on and off problem for a very long time, with about two different computers and several different microphones, so I know this is at least a reasonably common occurrence, but still, I see no solutions that work for me other than fiddling around with the recording settings and hoping it decides to work out well for me this time!

Here is the situation.
I plug in my microphone to one of the microphone ports, and it either works perfectly fine, or it
1. Is way too quiet for anybody to hear in Skype or any other communication program (though for some weird reason some recording programs still sound just fine)
Or 2. Picks up sounds from my computer, as in, other peoples voices, or just sound effects the computer is making.

This happens no matter the microphone, though sometimes if I switch back and forth between them it starts working. Same goes for switching back and forth between the front and back ports.
I've used both the realtek drivers and "high tech audio" drivers that seem to come with windows 7, and it happens with both of them.
Sometimes, changing the "effects" (as in, noise reduction, ac output, whatever) in the advanced settings fixes it, sometimes it doesn't.

This problem is NOT because of Skype, or any outside program. It's occurred on two different computers with different programs installed, and has also occurred on each computer both regularly and on an otherwise clean installation.

It is NOT from my audio settings. The more common problem is number 1, and this happens regardless of the volume settings on my microphone. I keep the recording volume at 100 at all times and increase or decrease the boost as needed (because it seriously isn't consistent at all).
When the problem happens, even putting the boost all the way up does nothing, and I have to put the microphone ON my mouth for it to pick up anything I am saying. Even when I do this, my voice is practically a whisper in the background of a bunch of white noise.

Hi Vriskus,
I had the same problem on an ACER Travelmate 5730G, Windows 7, 32.

Until yesterday, Skype worked fine, but today the volume of the microphone was suddenly very low. On Sound Recorder it was working properly.

I tried quite a few suggestions that I found on various forums.

I downloaded the Realtek sound driver from the Acer web site. After installation the Windows sound driver has been overridden and the sound is ok again.

I have installed the Realtek Audio Driver version Audio_Realtek_6.0.1.5911_W7x64W7x86_A