You can also use Renderd for network rendering. I have a compiled version at the link below (Windows and Linux).
http://www.crosscannon.com/modules.php? ... load&cid=1
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I've also seen this when the image folder you want to get to is under the "documents and settings" ... /whatever-username-you-use/my pictures/..../../ . Could be that blender doesn't like that it is nested so deep in subfolders with spaces.
Try this: Make sure that you have show hidden files turned on (Tools --> folder options). Then do a search for the .b.blend file. Its located just like theeth said. It's somewhere in *Drive*:/Documents and Settings/*User*/ try making a search there. Martin after the *User* folder look in the Applica...