Security is one of those topics you wish would just disappear — because then no one would need to think about it. But until that happens, we’ll end up trying to explain just what’s going on and how you can protect yourself, as happens in this discussion Adam has with Tech Night Owl host Gene Steinberg. follow link
Turn Off Filename Extension Warning
In Leopard, Apple fixed an annoying aspect of working with the Finder in Tiger. Previously, if you changed a file's extension, the Finder prompted for confirmation. But since no one has ever accidentally changed a filename extension, Apple thankfully added an option to turn that warning off in the Leopard Finder's preferences. Choose Finder > Preferences, and in the Advanced screen, deselect Show Warning Before Changing an Extension.
Adam Discusses Mac Security on the Tech Night Owl Live