that's weird that it would crap out right in the middle of something...did you check and make sure that the ua5 was still selected as the sound card? ya know, i think the problem is that 24/96 is not stable over usb, as has been debated before. perhaps the rig (i say that as i am not sure whether to specify drivers/recording software/hardware) just had enough of trying to take the 24/96 signal and just shit the bed.
becky, do extensive testing at home at 24/96, let it run for at least 2 hrs, and then repeat a few times!!! see if you get any dropouts or similar problems as this.
also, did you follow the advice i posted about setting up a laptop? it should in the archival section...anyways, those steps should help eliminate any other factors from causing disruptions in recording, ie. unwanted services taking up resources, etc.
i don't know too much about the buffer settings in wavelab (that's what you're using, correct?) but you may try playing with those and definitely post results of any and all tests so we can keep track of what you've done and what is left to try out. overall, good luck!!!