client version: 0.4.0-beta
os: windows7 64bit

My bitcoin's datadir folder is symbolic link to folder on removable drive (all of them is ntfs file system), when i use latest version from bitcoin.org it fail with empty error message box and crashed. In debug.log put 2 messages:

EXCEPTION: N5boost11filesystem316filesystem_errorE
boost::filesystem::create_directory: Невозможно создать файл, так как он уже существует: "C:\Users\rpman\AppData\Roaming\Bitcoin"
C:\Program Files (x86)\Bitcoin\bitcoin.exe in AppInit()

It's russian localisation, translated message is:

Can not create file because it already exists:

If remove symbolic link and make local copy, program starts and work fine.
Also -datadir command line argument to removable drive helps too.