I uninstalled oz messenger too. Like yahoo mess much better! You have to go to your service books settings/advanced options/service books and delete the one that says tmo oz instant mess! Hope this helps!
i'm on the Jivetalk bandwagon also! although it isn't free anymore, but if you use more than 1 client and like not getting charged for texts you'd probably be better of with JT.
i might as well uninstall OZ, i haven't used that in months.