After updating to 1.6.8 the game completely locks up as soon as i load into the game have to kill wow in task manager. Switching the version installed back to 1.6.7 fixes the issue.

You more than likely have something like MogIt installed. This happens when a new version comes out MogIt will cause the insane log as we update your cache to account for any new appearances added. If you have that or any mogging addon I'd suggest disabling those to update.

sounds good, ty