One very common cause for this type of problem is simply that the application is already running. Some applications should only be started once, and the application itself will check whether another instance is running before completing a startup.
In general, if this scenario were the case, we would expect the application to print an error to the screen or the debug.out file. However, not every application has appropriate error handling or messaging. This is especially true for custom applications, and it seems to be true for the application we are working with as well.
At the moment, we are making the assumption that our issue is caused by another instance of the application. This is an educated guess based on debug messages and previous experience. While we do not have any hard facts (yet) that tell us whether another instance is running or not; this scenario is quite common.
This situation is a perfect example of an Educated Guesser using...