Vista - C# Application Dies for Only 1 User

I have rather odd problem and I am not sure how to go about debugging it.
I have an MDI application that I am deploying on the local intranet to about
20 users using ClickOnce deployment. I am just using the default setting in
Visual Studio 2005 to deploy the app to an intranet web server. It is a full
trust application. After I published the last update one of the users called
and said the application would not start for him after the update installed,
but was working the day before. No other users are having problems.
Basically the problem is: The user starts the application it starts up
fine. Then the user clicks on another application that is open causing my app
to loose focus. When the user clicks back on my application it shuts down
within one second.
If the user starts my application and uses Alt+Tab to switch between the
applications that are running on the machine the error does not occur. In
fact if the user chooses to use Alt+Tab just once to switch between my app
and another app the problem goes away even if they start using their mouse to
start clicking between my app and another one.

Thanks,
Erik

Sounds potentially like an unhandled exception, you could try to put
try/catch blocks around all your entry events and find out if any of
them are tossing up exceptions.

I have added some additional logging to the app and can still not find the
root cause.

I had the user copy the application from the debug directory of my dev
machine and put it in the c:\temp directory.

The version in the c:\temp directory is not auto closing.

Erik