Hello, There are users that have run the Oxygen XML Editor on the Mac OS X Panther. However there are reports that the Panther install breaks the Apple Java VM on some systems. (A conflict between the Quick time libraries and Java) This means that no Java applications will run. An easy way to see if you have this problem is to open the the Terminal application, you will find it in your Applications->Utilities folder. Type the following command: java -version You should see the following message displayed: HotSpot not at correct virtual address. Sharing disabled. This means you have the problem. You can solve it by follwoing the steps: Rename: /System/Library/Frameworks/JavaVM.framework to /System/Library/Frameworks/JavaVM.framework.bak Next, load the Panther installer, and perform a "Custom" install of ONLY the "Essential System Software" (which includes Java). When it finishes, you will find a brand new JavaVM.framework directory, and "java -version" reports "builder 1.4.1_01-99", as it should. Once everything works, you can delete the JavaVM.framework.bak directory. Other solution is to force the editor to use the java 1.3.1 which is available on every Mac OS X platform. For this, open the oxygen.app bundle: CTRL-click on the icon, select "Show package contents", then open Contents and edit using the TextEdit application the file Info.plist, modifying: <key>JVMVersion</key> <string>1.3+</string> to: <key>JVMVersion</key> <string>1.3.1</string>