There are known issues with the Snow leopard plugin installation. To overcome this issue, You can either use ‘Firefox’ browser or open Safari in 32 bit mode.

Steps to set Safari to 32 bit mode.

Any Plugin on Mac requires that all the browsers are quit and the browser process is completely exited before upgrading. This is to ensure the previous version of the plugin is unloaded from the memory before upgrading it on the disk.

1. Close all the safari browser windows.

2. After closing all the instances of Safari, quit the application completely.

3. Open the ‘Applications’ Folder, right click safari and select the option ‘Get info’.

4.  Select the option ‘Open in 32 bit mode’ and close the dialog box.

5. You will be able to start the desktop sharing now with safari.