it is a problem with the digidesign architecture, i've been finding these threads all over AND have been providing a work around. after this i'm simply going to ask that you search the threads for one of those OTHER leangthy responses. but, for now.
download ASIO4ALL (v2). Google it, you will find it, the architecture is TRUE 32 bit (yes there is 64 as well) unlike digidesign which is actually two 16bit cores.
and it's a better made core as well. it is reverse engineered from the MAC Audio Core and has never let me down, i've been using it live for over 2 years worth gig'ing. once installed just locate the digi device your using and have fun. hope this helps.
like i said, google it. you'll find it.
and your welcome