How about some more information about your authoring setup:
Are you creating a single or dual layer disc?
How big is your project?
What is your menu structure? Do you have a main menu, scene selection menu, etc.?
Have you set any menu user operations?
Please give as much detail as possible... maybe something will stand out to one of us as being a potential problem.
It's also possible that it would work fine in Encore CS4, as Adobe often fixes bugs and integrates it into newer releases without releasing a fix for older versions.
Jon Geddes
Providing the Best Motion Menu Templates Available for Video Production
www.precomposed.com