Oh, sorry, Pam, I thought I had mentioned that the first thing I tried was to remove all mods. I only use the "No intro" and "NRAAS Master Controller" mods and even without them there was no change.
As Pam mentioned for the PC we are prompted to update the base game for each expansion, that has always been the way for me and I have never even thought of not doing it, so, yes, my game is updated to the latest patch.
The weird thing is, by method of exclusion, the problem is not from mods or from settings or from a bug, caused by the long use of the game, since with no mods, factory reset and reinstall it still persists. It makes me think it could be something more core-like. I could venture a guess that my old savegame's icons are glitched because the game has written their image information wrong, causing any re-draw to result in the same static noise image, but then new icons should not appear glitched and even after a reinstall and factory reset (i.e. reinstalling and NOT keeping my old "The Sims 3" folder in "My Documents") new icons are drawn as static noise.