As I mentioned here, I put together a monitoring and administration tool for the Microsoft Project 2007 Server queuing system. The system will optionally poll the heck of the system (generally not a good idea, but sometimes valuable) to see an almost real-time view into what is going on in the queue. ReadAllJobStatus expects a start and an end date, as well as the job states and message types you want to read from the queue. When I set my polling interval to almost zero (continuously calling ReadAllJobStatus) I was seeing an GeneralStartDateGTorEQFinishDate error even though I was using DateTime.AddSeconds(-10) to create a ten second gap between the start and end. As it turns out, the queue web service thinks two dates are the same unless there is at least a one minute difference between the two dates.
Just an FYI..