Subversion update skips new directories

Possible duplicate:
Subversion skips new directories during upgrade

From time to time we have problems with SVN when performing updates. It is very rare when someone adds a new directory doing an update via Tortoise does not work. If we do a "Fully recursive" update using the "Update from revision ..." option, then it will pick it up perfectly.

I poked around and saw this question, which is almost identical but unanswered . I found an element on the SVN website referenced by this post that talks about an issue in version 1.6.0 that has now been fixed. However, my SVN version is 1.6.9 and Tortoise is 1.6.7, so I would not expect this issue anymore.

It looks like new directories, never seen it for individual files.

We may have had early versions of Tortoise at some point (can't remember which one), so perhaps an issue was added to our repo that the update does not resolve.

We have a workaround, but it takes a few minutes to scratch my head after failed assemblies to figure it out, and people who haven't encountered this issue before really fighting until they ask someone else.

Does anyone know if this is a known bug and any permanent solutions?

Thanks.