Renderfarm error: Pre-Flight Error: Unable to import previously rendered file

Question

I have an error message I am receiving during network rendering on a  renderfarm, and was hoping for some help. The error is this: "Pre-Flight  Error: Unable to import previously rendered file."
Here is my setup and some details:
The user makes a comp, and adds it to the render queue set to render as a  quicktime movie file. Then they run a script which precomps everything  and sets it to render as a image sequence with "Skip existing files"  checked. This comp also has a post-render action set to import &  replace usage. After this comp is rendered, it gets pulled back into the  project and the original render item starts rendering the movie file  using the previously rendered image sequence as it's only layer.
This project gets saved to a server where our render nodes are watching  the folder. All the render nodes pick up the project and proceed to  render the image sequence. Then, after they are done, 1 machine will  pick up the second render item and begin rendering the image sequence  into the final quicktime movie.
All of this goes smoothly about 90% of the time. However, in some cases  an error shows up in the watch folder html page for the 2nd render item  (the one converting the image sequence to the movie). The error says  "Pre-Flight Error: Unable to import previously rendered file." After the  error occurs, no machines will start rendering the project.
My first guess is that the render engine on one machine somehow skips  rendering the image sequence comp, and then tries to render the  quicktime movie comp and fails because the image sequence has not yet  been rendered. However, I can't figure out why After Effects would skip  rendering the first comp.
Does anyone have any idea?
Thanks for the help, and let me know if you have any more questions about the setup,
Adam

Answer 1

Well, you should get used to the fact that it's simply gone... Just looking at your screenshot makes me grind my teeth. From delayed writing of files to fragmentation in user folders to Windows doing obscure things this could be anything, but seriously, saving important files on the desktop? That is simply sloppy data management. There is no other way to say it. Read up on what proper file naming, incremental saving and backups are good for and why keeping work files separate and away from your user home directories is actually a quite simple, yet effective concept to avoid exactly that kind of issue.
Mylenium