I don't even know where to begin to diagnose this one. Usually, when a command finishes, the prompt prints itself for the next command. However, that is not happening. Hard to explain with words, I'll just use an example:

User@Machine:~$ cp /mnt/mountname/directory/textfile.txt .

After waiting several seconds (far too long for this operation on a small file) I press Enter, and see:

User@Machine:~$ cp /mnt/mountname/directory/textfile.txt .
User@Machine:~$
User@Machine:~$

So clearly the operation had finished, but the prompt didn't display... until I pressed enter, and then BOTH prompts instantly displayed.

This error does not happen with commands like cd.