I am trying to model a simple dinosaur claw.  When I go to smooth my lo-res mesh, I keep getting edges/corners that will not smooth.  I have deleted history and merged.  Any help would be great.

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smoothing1_2009.zip

Are you able to zip and upload your scene?  It looks like you might have some duplicate geometry, perhaps made accidentally by too many Extrude operations.  Its hard to tell though without having the actual scene…

3ds Max 2013, Maya 2013
Windows 7 Ultimate 64 Bit
Core i7, 12GB RAM
Nvidia Quadro FX 3700 (Driver 267.17)

I took a look at your file.
A very frustrating problem because it was not obvious at first.
Somehow while your verts are all merged, your edges remained unmerged.

If you go to DISPLAY - POLYGONS - BORDER EDGES you will see where you have a hole or un merged edges. which is what your problem was here.
Just select the unmerged edges (go to DISPLAY - HEADS UP DISPLAY - POLYCOUNT and you will see that you have two edges selected instead of one.)
Then just go to POLYGONS - EDIT MESH - MERGE and you will see the problem go away.

Here is the fixed test file just for fun.
All the best.
~Ben

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smoothing1_fix.zip

Ben,

THANK YOU!  I appreciate you not only solving the problem but sharing your techniques for tracking down the cause.  Now I see what I had been doing wrong.  I had been selecting the whole mesh (in object mode) and then Edit Mesh > Merge.  This merges verticies, but not edges.  So, when I followed your steps (selecting both overlapping edges in component mode, and then Edit Mesh > Merge), and it works perfectly: the overlapping edges become one single edge, and subsequent smoothing works perfectly.  Thank you!

Mike