I seem to be regularly encountering a problem with SQL Dependency Tracker in that it appears to hang when I switch to another application such as Excel or SQL Data Compare. As I need to use the information presented by SQL Dependency Tracker to compare tables, etc., I switch back and forth quite frequently.
It doesn't happen immediately, but after a period of about 10 to 15 minutes, any attempt to switch back to SQL Dependency Tracker fails. Task Manager reports that it is Not Responding, and the only course of action is to End Task. This is not ideal, especially if I was building a complex dependency diagram, and all changes would be lost.