Common issues
From 360Works Product Documentation Wiki
Webviewer is black or has Red X
This happens because Java now requires the same jars for applets as it does for webstart. All 360Works plugins had to be redeployed to comply with this. The solution is to use the latest version of the all 360Works plugins.
Unsupported class version
This can happen on Leopard if /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK is symlinked to 1.6 instead of 1.5 as on most systems. This is a problem because Java 6 on Leopard is 64-bit and FileMaker is a 32-bit application. Update all 360Works plugins to the latest version.