At least one other guildy has mentioned they are also freezing on teleports and have to hard exit WoW and restart. About 80% of the time I take a portal or hearthstone I freeze. Not on instance zoning though.
GM of course gave the only answer GMs ever give --deleted add ons and start from scratch.
I was hoping someone had a more. . . enlightened idea.
If you have Gatherer installed, that's what's doing it. I had an issue where I would freeze everytime I hearthed or ported from the new island back to Shat. I finally dug up some info that linked a buggy file in Gatherer as the culprit, updated the mod and it remedied the situation immediately.