from what I am seeing, this is a fairly common issue under windows, (not specific to irrlicht)
I think you are getting this common error through irrlicht because your version of irrlicht is one built on windows?
I probably sound stupid because I'm trying to guestimate this issue, I have only ever used windows approx 8 months of my entire computer years.
But I found this, not sure if helpful..., seems close to sofar's answer but seems more tied into libpng (but he is correct imagemagick is your solution, just a diff command to try in the answer in the link
http://stackoverflow.com/questions/22125146/how-to-fix-libpng-warning-when-reading-interlaced-png to answer your question about targeting which files are causing this error, it is basically any alpha textures, including dirt w/ grass sides, because the grass sides texture uses alpha transparency. (as I think morn mentioned?)
And this isn't even specific to the graphics card either, this seems to be (as I stated) a fairly common windows ... issue, and how it handles transparency, explorer 6 had a big issue with this too I guess? At a time when most other browsers did not (go figure)... it's something deep in the binaries of hades/// :D
edit: (btw, if I am making no sense and only inflating the problem, someone kindly let me know? and I will fade off slowly into the backdrop :D )