Here's how to reproduce the problem: mount a share, create a new, empty directory, then in that directory, create two entries: a file named abcdefghijkl.txt a directory named abcdefghijkl in _this_ order. Open a dos window and try to "cd" into the newly created "abcdefghijkl" directory, it is not possible. If you reverse the creation order, the problem isn't there. Unfortunately, wincvs triggered this bug. :(
Sorry, my fault, forget it: mangled names was set to no. Still, it is interesting that it worked in 2.2.3 with the same config.