Marvin --
Well, that error message really helps to troubleshoot the problem!
OK, since the software won't give us any information, let's try a different
approach. What happens if the PM in question does the following:
1. Launch Microsoft Project Professional 2007 and log into Project Server.
2. Open a project containing pending tasks updates.
3. When prompted to review pending task updates, click the Yes button.
4. In the Task Updates page shown inside of Project Professional 2007,
select the updates to accept and then click the Accept button.
5. Click the "click here" link to see the updates in Project Professional
2007.
6. Save and publish the project.
Let us know if the PM in question can process the updates within Project
Professional 2007 using the steps above.