VS 2005 Unhandled Exception problem on vista

Hi
I am worked on a vb.net program in win XP. I upgrade my windows to vista
and working on my program in this.
When I start the application under debugger. If my program encounter to
problem,
windows vista show windows error message and close my program. but I not get
any message for unhandled exception from visual studio.
also VS as just-in-time debuggeris registered.(Tools | Options | Debugging |
Just-In-Time | "Managed"
)
how can i fix this problem?
thanks