When I try to start the DevPartner Agent Manager on my Windows machine I get an error which states that as error has occurred during initialization and the Agent Manager UI won't start.
The DevPartner Agent Manager in version 6.6 is a Java Swing application which includes the Java runtime. Your computer display setting must be at least 256 colors for Java to initialize this UI. Having the display set to 16 colors will cause this initialization failure.
Once you change your display color setting, you should be able to start the DevPartner Agent Manager without error.