You can enable access to the clipboard from Java applets by editing the java.policy file in the JRE (Java Runtime Environment) lib/security directory. On Windows, this will be a file such as:

C:\Program Files\Java\j2re1.4.1_01\lib\security\java.policy

Edit this file and look for the general-purpose grant entry, which grants permissions to all applets. Add the following setting to this section. For example:

grant {

// Leave existing settings..

// Try to renable the clipboard access.
permission java.awt.AWTPermission "accessClipboard";
};