A problem has started occurring recently in which some new files added to the subversion repositories don\'t get pulled down to other clients after doing an Update.
The only thing that I can think of is maybe it has to do with the 1.5 to 1.6 transition? Make sure everyone has a 1.6-based version of tortoiseSVN and try again perhaps.
Also, the way you are phrasing the question makes it sound like you are using SVN for distribution of files instead of concurrency. If that is the case, consider a tool like Unison instead of SVN.