I've tried deactivating all of my mods and the problem wasn't fixed. I also tried deactivating the DLC I have (Dawnguard and Hearthfire, I haven't bought Dragonborn yet) but that didn't work either so I must conclude that for some reason the "disenchant" part of the arcane enchanter is bugged.
Do I need to reinstall or run some program to diagnose and fix the problem?