No options when USB devices attached ?

Can anyone tell me why whenever i plug in a USB mass storage device such as a memory card or flash drive i no longer get the screen asking me what i want to do next i.e open to view files and folders etc . I always have to open my computer to select the drive or card as it will not automatically present me with the screen i was once familiar with . Im running XP Pro SP2. Many thanks

Thanks , i'll try that