I have Minecraft installed on SMB network share which mounted on Windows workstation as local drive "F:". And my %APPDATA%\.minecraft folder is symlink to "F:\mincraft". Don't ask why, it just works so. I decided make clean install of MC 1.6.1 but MC can't load level with error

Client> Error in class 'CodecJOrbis'
Client>     Unable to acquire inputstream in method 'initialize'.
Client>     ERROR MESSAGE:
Client>         minecraft:sound/random/click.ogg

After short researching I found that some of internal resources was named in uppercase. For example "..\minecraft\assets\SOUND\" or "..\minecraft\libraries\COM\". After renaming all folders to lowercase all works fine. Seems like folders are not creating correctly by default.