I can lock the door on the driver''s front door using the power lock switch, but it will not unlock unless I manually lift the lock lever. In addition, when locked, I cannot unlock the door from the outside with a key. Any ideas what part I need to fix this? Could it be a bad actuator?

Depending on what year your P/A is, The most common problem is on the end of the actuator there is a little rubber piece that connects the actuator arm to the lock/latch and the rubber piece tears so the actuator arm slipps out and only works one way. We used to be able to get just the little rubber boot from the GM dealer but I havn''t tried to get one of those for a long time. If you get a new actuator it will come with a new rubber thing on it. I would guess maybe your lock rod came off and that is why you can''t unlock the door with the key unless the key wont even turn then you probaby need a new lock cylinder.