I'm totally non technical, but this works for my much inferior system: /flush. Frequently and often. And lots. And other such synonoyms.
I have it as a hotkey on all my chars because it plain and simply helps prevent the otherwise guaranteed lockups I'll get after a while of playing. My husband, who has almost exactly the same hardware *and* software on his rig, doesn't get those at all. (Makes me miss the simple good old days of my Mac.
)
I realise this is more of a workaround than a fix, but I'm almost positive it'll help. At the very least it won't hurt.