It sounds like you're using the Timer that's in the Toolbox. This is a timer that depends on Events in order to notify your application of the Tick. This also means it runs entirely on the UI thread (the thread your application started up on). When the thread is running your check every 10 seconds, it can't do other things, like update the UI (repaint it) and respond to user clicks.
The only solution to that is to move your checking code to a background thread. That is easily accomplished by removing the Timer you dropped on the form and instead use the System.Threading.Timer
] class. It's callback will use a ThreadPool thread to execute your check code.