Application Freezing on ALT-TAB

Hi,

I have windows application written in C# and I am calling 2 popups on main form.

e.g. Form1 calling Popup1 and Popup1 calling Popup2 using showdialog().

however, if on Form1 , if hit button call Popup1 and meantime I switch to different application, my applicatino is freezing.

i really don't know what went wrong in my code.

if i don't switch to diff application (MS word, outlook) then it is working fine.

Thanks

Vikram

Thanks In Advance, Vikram