After playing some more and finding out that Age of Conan still freezes on me half of the time that I use my Pillar of Infernal Flame combo, I searched high and low for suggestions on how to fix it. And one guy on the forums suggested to disable sound, a check box which is suspiciously marked with a mouse-over text saying "disable this if the sound system causes crashes". So I disabled sound, and played for hours without having a single crash.
I have a nForce 680i SLI onboard sound card with a Realtek chip, and before you ask, yes, it has the latest drivers. This is not a very exotic motherboard, and with onboard sound cards being quite good nowadays, there are lots of people without added sound cards around. This same sound card plays every other game I have without problems, only for Age of Conan I have to disable it to play. :(
Now my options are "play without sound", or "buy a sound card", both of which are equally unattractive. I would much rather have some option in AoC to turn of spell sound, and still get the other battle sounds, music, and voice overs. Anyone got an idea how to fix this?