HyperDA is a larger-than-average desk accessory. It must use a complex series of buffers to build up images of cards, and these occupy memory. With other applications that require large amounts of memory, particularly any such applications that are “ill-behaved” (i.e., failing to conform completely to Apple’s design guidelines in memory management areas), you should caution your users not to open the desk accessory when they are running an application that doesn’t allow at least 65K bytes of free space for other applications or desk accessories.