Despite the instruction booklet saying it's compatible with MacOS, the pen simply won't mount. Tried everything from reformatting it to FAT16 to FAT32 but nothing will get it to appear on the desktop. VERY disappointing. Tried with OX X 10.3.9 and 10.4.11.
Worse still, plugging it in locks up the Mac's USB ports so the Mac is then unable to detect when new devices are added, and disables Sleep mode, so if you try to put the computer to sleep it just hangs. The only way to recover from this is a restart or shutdown.
It works fine however in Windows XP.