This type of record relates to a cache or cookie item that Microsoft Internet Explorer was unsuccessful in removing. This may have been due to the file being locked or in use when the attempt was made. This record would have originally been a URL record that had subsequently been updated to LEAK status to indicate it could safely be removed at a later stage. LEAK records are often incomplete and may not show the full original URL.
The cache scavenger periodically cleans items from the cache. If an item is added to the cache and the cache is full, the item is added to the cache and the cache scavenger is scheduled. If the cache scavenger completes a round of scavenging and the cache has not reached the cache limit, the scavenger is scheduled for another round when another item is added to the cache. In general, the scavenger is scheduled when an added item puts the cache over its size limit. By default, the minimum time to live in the cache is set to 10 minutes unless otherwise specified in a cache-control directive. When the cache scavenger is initiated, there is no guarantee that the oldest items are the first to be deleted from the cache.
When an item is scheduled for deletion, it is marked as a LEAK entry.