Ducting Systems and Air Ventilation - Request Some Help - Supply Duct - Possible Condensation Leak?

Hello. I looked up today and found water spots around a supply register in my house. I went into the attic, dug out all of the insulation (about 2 feet of it, and all on top was dry).

Where the ductwork connects to the vent looks like this (side view):
http://novembermike.smugmug.com/photos/655461370_4NK6q-S.jpg

On the other side of the lower 2x4, I found a 1.5 foot area of water accumulation. It is wet from the point where the ductwork connects to the 2x4 (not sure why it connects to it ...) and then spreading out to this area (top down view):
http://novembermike.smugmug.com/photos/655461383_7dR3N-S.jpg

I've never done any work in this area, so I didn't want to try and disconnect the ductwork from the register. Can anyone suggest what possibly could be causing this?

Many thanks in advance for your responses.

hard to tell from the pics. Is the wood wet at the duct?

hard to tell from the pics. Is the wood wet at the duct?

The duct itself does not feel wet, just the wood around where the duct meets the ceiling.