For some unknown reason, Netscape default settings do not allow graphic files to be downloaded from java programs.
To fix this add the following command line to the file C:\Program Files\Netscape\Users\your_user\prefs.js

user_pref("security.lower_java_network_security_by_trusting_proxies", true);

Note in the file name above "your_user" is unique to your browser.

This fix seems to work Netscape 4.5 but not for 4.0.x.

If your game response is slow (because you have an underpowered machine) you may want to change the color settings for your display while playing the game. To do this double click My Computer and then double click the Control Panel. Under the Control Panel double click the Display folder. Click on the "Settings" tab and under "Color Palette" select the "256 color" option, then click OK. You can switch back to your default setting after you have finish with the game.