Today Microsoft released the GDR/Update build (kind of ServicePack 1) for SourceSafe 2005.
The update targets improving the compatibility with VisualStudio 2008, Windows Vista and fixes a couple of bugs affecting performance, stability and reliability (most important, IMHO), plus a few customer annoyances.
You can download the update from this Visual SourceSafe 2005 Update MSDN page. If you're running Visual SourceSafe 2005, it is strongly recommended to upgrade your build.
Richard Berg maintains in his blog a more detailed list of the bugs fixed.