click event not fired after enter event handler takes long time

I have a Form which contains a Button (button1) and two event handler:

1. a handler (button1_enter) for the Enter event;

2. a handler (button1_click) for the Click event;

When the focus is on another control (not on the button1), when the button1 is clicked then the button1_enter and the button1_click are correctly invoked. My problem is when the button1_enter handler takes long time to be executed, let's say one minute, than the button1_click is not invoked. It seems like there is such as a time out that empties the handlers list... Why isn't it invoked? how can I ensure both handlers get called even if the first takes long time?

Thanks a lot for the help

Cesare

PS: I can't do everything into the button1_enter handler, they have to stay separated.