FWIW I captured a scenario where FreeCol hangs after the next click: It doesn't matter what you do with the active unit, nothing (sentry) is fine. After that the last unit is shown, and all I can do at this point is kill FreeCol 0.10.7 hanging in a Window 7 JRE 1.6u45.
Looks like a duplicate of BR#2523, which is fixed in trunk. Have a look at your merchantman "Halve Maen" --- it is trying to go to the high seas tile next to it, but is blocked by another ship. To workaround, just change the tile it is
aiming for.
Will close this soon in the absence of other problems.