why does “program not responding” freeze shut down on one machine but not on another? [duplicate]

why does “program not responding” freeze shut down on one machine but not on another? [duplicate]

I often get "program not responding" issue on my Windows XP Pro machines during shut down. However, one machine just ignores it and shuts down. But the other essentially freezes until I manually say "end task", and that is very inconvenient.