Windows Forms Application routines stop while Form Window is open

  asynchronous, c++, forms, taskbar, windows

Firstly, sorry any english mistakes since I’m not a native english speaker.
The problem is that, I have a windows forms application that is responsible for control the daily workload of my customer’s employees both while working at the office than while working at home. It’s a Windows application that runs in two ways, as a service and as a taskbar icon, that opens a simple window in which the employee can see his/her time limit of the day and ask for extra hours to his/her supervisor if needed.

I hope the description of my application is clear enough for those who read it, but here is how the application should work: that application locks the user’s pc if he/she exceeds the permitted workload limit, and if he thinks he/she might need some extra hours, he can unlock his/her’s pc (by entering his/her password), and in a time limit of 30 seconds click on the Taskbar’s icon and use the application’s commands to ask for extra hours.

The problem is: while the form window is open, the application’s routines stop working, so, if the user keep it open, the application won’t lock the pc again, what can be threated as a breach in the system. Do someone have an idea of what could be happening and something I could check in the system? Before you ask for code samples, it’s a huge system and I’m no the first person to work on it, so I don’t know where I should look (to be honest, I tried a lot of solutions, some found here in Stack Overflow).

That’s the last thing I tried, but while the form is open, it stops running as well.

if (Principal.Visible)
            else if (Session.system_active)  

            aTimer.Interval = 30000;
            aTimer.Tick += new EventHandler(timer_Tick);

Source: Windows Questions