Hi all!
I've tried to use Indirect Light by just enabling it on Render Settings, and it worked... most part of it at least. But it darkened all shadows and ambient occlusions, and made the entire scene overall darken (not only shadows and AOs, but walls and ground too). I was under the impression it would only add more lighting (the indirect lighting), and not darken anything. Did I miss something? I'm using one IBL light only, and I was indeed able to see the indirect light bouncing off into nearby surfaces, so besides the darkening of my scene, it worked just fine.

 IBL doesn't "go through walls" when using IDL.  So if your scene is in room, IBL won't work.  Have you tried Point lights?

IBL will work in a room, but it will work incorrectly.  Although some users have found a balance between IBL and IDL (this is assuming you are working with P8 or PP 2010), it is totally unnecssary to use both.  And although you could use 1 IBL to illuminate, it is not the recommended mode to achieve a more realistic lighting situation.  You have not provided enough information about your scene for us to make a appropriate accessment.  Could you show us the problem render and more tech info?

I hold the view that IDL has really superceded IBL. That's not to say that you can't experiment using both together, if you have something particular in mind, and understand the limitations of using both together. Otherwise, like hborre, I would not advise it.

When setting up a scene I do fast test renders with IDL off and with a desaturated HDRI IBL light switched on. When I get to the stage of IDL lighting setup, the IBL light gets deleted. (Some say it can slow down renders even when turned off - I have not yet tested this).
 
Also note that all light-based AO is automatically disabled when using IDL.
Material-based AO will only work if you enable it in each AO node in the Advanced Material Room.

yeah, ibl/ao bad now, but look at bill's dome. it's in effect an HDRIBL, altho not falling into
any of the poser lite categories.