A memory leak occurs when you press F5 to convert a character code to some specific kanji characters in the Japanese IME module in Windows Vista or in Windows Server 2008
On a computer that is running Windows Vista or Windows Server 2008, you use the Japanese Input Method Editor (IME) to input some characters in an application. When you press F5 to use the translation method that converts the character code to some specific kanji characters, a memory leak occurs. Therefore, the application that hosts the IME may stop responding if F5 is pressed many times.
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB2205122.