I'm going to have to agree with GSquared on this one. This definitely does not belong in a trigger and as Gail said the trigger runs on the server so where would the pop-up show up?

I'd be interested to see the resources you found about triggers and how you are using triggers. Typically you try to limit the amount of work done in triggers. You either do the work in a a stored procedure or the business layer of the application.

Have you read this article[/url] here on SSC?