open file dialog not working in vista and 2008 environment

i am using Vista . I designed MSi file through Visual Studio 2008 Setup 开发者_如何学Cand deployment project in which I added one custom action. In the custom action, I am opening OpenFile dialog. This Open File dialog is not showing mapped drive or network locations. Can anybody help???

Is the custom action running with elevation? This is a problem with UAC: elevated tokens cannot see mapped drives or network locations associated with the original, non-elevated, account.