Some time is not possible back to parent directory.
You can reproduce this on 2 ways (maybe more)
1) Go to File Module
2) browse on folders up and down without problem
3) click on refresh
4) The link "Up" to go parent directory don't work
1) From favorite link select one of your defined favorite dir
2) You can browse down into directory but can't go up to parent.
Sorry I hope you understand. My english isn't so good.