Apple fun!
How to check for—and get rid of—a Mac Flashback infection This article has a clean simple showing of how to check and remove it from your mac. It surprises me that so many long time mac users dont know how to use terminal.
This kind of baffles me, there is no default screen lock for the Snow Leopard desktop. Either way, to enable it go into /Applications/Utilities/ and click on keychain access. Under the keychain access menu, click preferences, then click show status in menu bar. A little lock will appear in the menu bar. You can now click it and lock the screen. Hope that helps others!