Chris Sells and his homies won't admit it openly but Windows Forms 1.x is brittle. I was just remarking yesterday that the jump from ASP to ASP.NET was serious quantum leap. Going from a VB6 form to a Windows form is like skipping around a bit.
First of all, threading is the problem. Windows Forms 2.0 will take care of this problem (we hope) with the Background Worker thingy. However, I
have moved out of Access forms and into Windows forms with reckless abandon.
ASP.NET applications are worth your time. They will not break your heart. Windows Forms are still toys. You can open a Windows Form designer and your controls can mysteriously vanish and then reappear after closing VS.NET. Let's see the next version.