I'm not sure to understood your situation. You said:
I sold my old machine to Larry Rhodes and he emailed me that some of his programs will not activate.
What do you mean with "his" programs ? Is he trying to activate HIS own Serial Numbers for these products on the PC you sold to him, but they are failing the activation ?
Has the system being reformatted ? Or, maybe, he's using your own Windows installation, so the Serial Number in the registry are still YOURS instead so, he's not really trying to activate HIS own Serial Numbers, but just reactivating yours ?
I assume this is the issue, and if yes, Deactivating should be enough, but after a Deactivation, he should use HIS own Serial Numbers. Deactivating will allow to re-insert the Serial Number, removing the old one from the registry.
If you or him made some mistake, and ran out of activation, it's no problem, just email me (both of you), each one with your Serial Numbers that don't activate anymore, and we'll add new activations.
Of course, you cannot both use the same Serial Numbers, that would be against the license...