I tried Leopard Cache Cleaner 4.0.2 with 10.5.1. I reviewed the documentation and did not have any applications open other than Safari when I used LCC 4.0.2. I have a 2.16 Ghz MacBook with 2GB of Ram. I was very disappointed as after I chose Optimize System - Optimize Files, I had at least eight applications completed deleted including Mail, Quicktime 7.3, TextEdit and several other applications, three which were in the dock and changed to the application icon with the black question mark. The common symptom I observed that may be helpful to the developers were all eight of the applications, and also files associated with the "Recent" use, were the files/applications deleted. Fortunately I had backups of all applications and all but one of the files.