Odd USB problem

I brought 2 identical eSATA harddisk dock station.  One of them were connected to my Lenovo S12 Netbook.  Since 3 days ago, I kept experiencing this USB dock kept disconnect and connect again, causing the Recorded TV video I paused (played from a harddisk on that dock) failed to continue.  That was extremely annoying.  So last night I finally had enough, and swapped this one with the one using in my closet server computer. 

The problem was NOT happening on this another one.  So I though, hack, see, so the previous one has problem, and must return it as soon as possible.

The odd thing, though, was that after I swapped back, I still DID NOT experience the constant disconnect and reconnect problem.

So now I really don't know whether the dock has problem, or the simple reconnection solved the problem.  will see.