Images not found

two quick ones for you all.

i have created a dynamic picture loader which loads in external jpgs, if a jpg is not there, the movie freezes and needs re laoding. Is there any way i can get the movie to look for the image, if its not found in say two seconds, abort the loading of the image, and carry on.

Also, is there any way to (there must be a way) to halt flash from loading an image half way through loading, and load another, currently my movie simply continues loading a jpg until its finished,

many thanks

jamo