I've just upgraded to 1.6.2, and I've started completely fresh by deleting all contents of the .minecraft directory.

The launcher downloaded and started 1.6.2. The first click on a button in the menu worked as expected, however, no click sound was played. On the second click, the game froze completely, I had to kill javaw.exe with Task Manager. I've retried multiple times, freeze always occurred at the second button click. This rendered the game unplayable.

After kill, the launcher always displays the following error (full log attached):

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

I noticed that the capitalization of the directory name isn't consistent with the actual contents of the directory .minecraft\ASSETS, the subdir was named 'SOUND' and not 'sound', as it is spelled in the log. So I renamed the directory to 'sound' and tried again, and hooray, it worked.

I don't know why this bug doesn't affect all users, maybe it's because my .minecraft is symlinked to a network share, which is served by a Linux server running samba. Windows NTFS is case preserving, but not case sensitive, but the file system on the server is case sensitive.

Please keep the names of files and directories which are installed consistent with how they are referenced in your code. It is bad practice to make assumptions about file system properties like case handling, which are inconsistent across platforms.