I've sometimes have the problem that a regular Tortoise SVN 'update' doesn't give me all files in a directory. I have not found how to reproduce the problem, but usually I have a directory with some files already checked out, and a file is added to the repository by a co-worker. There is no warning that some files are omitted; it's usually an argument between me and my co-worker that shows that we have a missing file :)
With an fully recursive update (see Tortoise SVN update recursively) I do receive the file, but I would like to know what is going wrong. We never use partially checkouts (so, setting Tortoise SVN to always do a recursive update would be a hack to fix this).
Edit: working directory is on local disk. It has happened to various co-workers.