When working on dual screen machines, if you launch the Microsoft Project, and then move it from Primary to Secondary display before attempting to integrate with Web TimeSheet (by selecting Web TimeSheet Integration… from the Tools menu), this problem might occur.

You would find the Web TimeSheet Integration Manager setup window, however, when you select OK, the main Integration Manager interface will not work.

Work Around:
Always keep the Microsoft Project application opened on the primary display (monitor). Once you have encountered this issue, you must close and reopen the Project, and ensure that the Project is accessed only from the main display to initiate the integration process.