Java
The crossword software uses java and is tested on pc's and mac's, both old and new. You may still experience difficulties though, for instance because you have Windows XP which may not include java. Also, some older java versions are known to have bugs.
In almost all cases, these problems can be solved quickly by downloading the latest version of java. Downloading is free and installing easy.
The latest java-plugin for Windows (except Windows 95) can be downloaded for
free (installation is automatic) from this page:
http://www.java.com/en/ (click 'get it
now')
For Windows 95, please visit this page:
http://www.java.com/en/download/help/win95.jsp
Java is already installed on an Apple Macintosh with OS X. Puzzlers using a
Mac with OS 8 or 9, can download the free plug-in (MRJ 2.2.5) from this url:
http://developer.apple.com/java/classic.html
Java for systems not mentioned above, can be found via this page:
http://www.java.com/en/download/manual.jsp
In case installing the latest Java-plugin did not work, please check your security settings. Very strict security settings of your operating system, anti-virus software or a firewall may prevent java to work properly.